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2024-09-18Merge tag 'perf-core-2024-09-18' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf events updates from Ingo Molnar: - Implement per-PMU context rescheduling to significantly improve single-PMU performance, and related cleanups/fixes (Peter Zijlstra and Namhyung Kim) - Fix ancient bug resulting in a lot of events being dropped erroneously at higher sampling frequencies (Luo Gengkun) - uprobes enhancements: - Implement RCU-protected hot path optimizations for better performance: "For baseline vs SRCU, peak througput increased from 3.7 M/s (million uprobe triggerings per second) up to about 8 M/s. For uretprobes it's a bit more modest with bump from 2.4 M/s to 5 M/s. For SRCU vs RCU Tasks Trace, peak throughput for uprobes increases further from 8 M/s to 10.3 M/s (+28%!), and for uretprobes from 5.3 M/s to 5.8 M/s (+11%), as we have more work to do on uretprobes side. Even single-thread (no contention) performance is slightly better: 3.276 M/s to 3.396 M/s (+3.5%) for uprobes, and 2.055 M/s to 2.174 M/s (+5.8%) for uretprobes." (Andrii Nakryiko et al) - Document mmap_lock, don't abuse get_user_pages_remote() (Oleg Nesterov) - Cleanups & fixes to prepare for future work: - Remove uprobe_register_refctr() - Simplify error handling for alloc_uprobe() - Make uprobe_register() return struct uprobe * - Fold __uprobe_unregister() into uprobe_unregister() - Shift put_uprobe() from delete_uprobe() to uprobe_unregister() - BPF: Fix use-after-free in bpf_uprobe_multi_link_attach() (Oleg Nesterov) - New feature & ABI extension: allow events to use PERF_SAMPLE READ with inheritance, enabling sample based profiling of a group of counters over a hierarchy of processes or threads (Ben Gainey) - Intel uncore & power events updates: - Add Arrow Lake and Lunar Lake support - Add PERF_EV_CAP_READ_SCOPE - Clean up and enhance cpumask and hotplug support (Kan Liang) - Add LNL uncore iMC freerunning support - Use D0:F0 as a default device (Zhenyu Wang) - Intel PT: fix AUX snapshot handling race (Adrian Hunter) - Misc fixes and cleanups (James Clark, Jiri Olsa, Oleg Nesterov and Peter Zijlstra) * tag 'perf-core-2024-09-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits) dmaengine: idxd: Clean up cpumask and hotplug for perfmon iommu/vt-d: Clean up cpumask and hotplug for perfmon perf/x86/intel/cstate: Clean up cpumask and hotplug perf: Add PERF_EV_CAP_READ_SCOPE perf: Generic hotplug support for a PMU with a scope uprobes: perform lockless SRCU-protected uprobes_tree lookup rbtree: provide rb_find_rcu() / rb_find_add_rcu() perf/uprobe: split uprobe_unregister() uprobes: travers uprobe's consumer list locklessly under SRCU protection uprobes: get rid of enum uprobe_filter_ctx in uprobe filter callbacks uprobes: protected uprobe lifetime with SRCU uprobes: revamp uprobe refcounting and lifetime management bpf: Fix use-after-free in bpf_uprobe_multi_link_attach() perf/core: Fix small negative period being ignored perf: Really fix event_function_call() locking perf: Optimize __pmu_ctx_sched_out() perf: Add context time freeze perf: Fix event_function_call() locking perf: Extract a few helpers perf: Optimize context reschedule for single PMU cases ...
2024-09-10Merge branch 'perf/urgent' into perf/core, to pick up fixesIngo Molnar
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2024-09-10perf/x86/intel: Allow to setup LBR for counting event for BPFKan Liang
The BPF subsystem may capture LBR data on a counting event. However, the current implementation assumes that LBR can/should only be used with sampling events. For instance, retsnoop tool ([0]) makes an extensive use of this functionality and sets up perf event as follows: struct perf_event_attr attr; memset(&attr, 0, sizeof(attr)); attr.size = sizeof(attr); attr.type = PERF_TYPE_HARDWARE; attr.config = PERF_COUNT_HW_CPU_CYCLES; attr.sample_type = PERF_SAMPLE_BRANCH_STACK; attr.branch_sample_type = PERF_SAMPLE_BRANCH_KERNEL; To limit the LBR for a sampling event is to avoid unnecessary branch stack setup for a counting event in the sample read. Because LBR is only read in the sampling event's overflow. Although in most cases LBR is used in sampling, there is no HW limit to bind LBR to the sampling mode. Allow an LBR setup for a counting event unless in the sample read mode. Fixes: 85846b27072d ("perf/x86: Add PERF_X86_EVENT_NEEDS_BRANCH_STACK flag") Closes: https://lore.kernel.org/lkml/20240905180055.1221620-1-andrii@kernel.org/ Reported-by: Andrii Nakryiko <andrii.nakryiko@gmail.com> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Andrii Nakryiko <andrii@kernel.org> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240909155848.326640-1-kan.liang@linux.intel.com
2024-09-10perf/x86/intel/cstate: Clean up cpumask and hotplugKan Liang
There are three cstate PMUs with different scopes, core, die and module. The scopes are supported by the generic perf_event subsystem now. Set the scope for each PMU and remove all the cpumask and hotplug codes. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240802151643.1691631-4-kan.liang@linux.intel.com
2024-09-05perf/x86/rapl: Fix the energy-pkg event for AMD CPUsDhananjay Ugwekar
After commit: 63edbaa48a57 ("x86/cpu/topology: Add support for the AMD 0x80000026 leaf") ... on AMD processors that support extended CPUID leaf 0x80000026, the topology_die_cpumask() and topology_logical_die_id() macros no longer return the package cpumask and package ID, instead they return the CCD (Core Complex Die) mask and ID respectively. This leads to the energy-pkg event scope to be modified to CCD instead of package. So, change the PMU scope for AMD and Hygon back to package. On a 12 CCD 1 Package AMD Zen4 Genoa machine: Before: $ cat /sys/devices/power/cpumask 0,8,16,24,32,40,48,56,64,72,80,88. The expected cpumask here is supposed to be just "0", as it is a package scope event, only one CPU will be collecting the event for all the CPUs in the package. After: $ cat /sys/devices/power/cpumask 0 [ mingo: Cleaned up the changelog ] Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lore.kernel.org/r/20240904100934.3260-1-Dhananjay.Ugwekar@amd.com
2024-09-05Merge branch 'perf/urgent' into perf/core, to pick up fixesIngo Molnar
This also refreshes the -rc1 based branch to -rc5. Signed-off-by: Ingo Molnar <mingo@kernel.org>
2024-08-25perf/x86/intel: Limit the period on HaswellKan Liang
Running the ltp test cve-2015-3290 concurrently reports the following warnings. perfevents: irq loop stuck! WARNING: CPU: 31 PID: 32438 at arch/x86/events/intel/core.c:3174 intel_pmu_handle_irq+0x285/0x370 Call Trace: <NMI> ? __warn+0xa4/0x220 ? intel_pmu_handle_irq+0x285/0x370 ? __report_bug+0x123/0x130 ? intel_pmu_handle_irq+0x285/0x370 ? __report_bug+0x123/0x130 ? intel_pmu_handle_irq+0x285/0x370 ? report_bug+0x3e/0xa0 ? handle_bug+0x3c/0x70 ? exc_invalid_op+0x18/0x50 ? asm_exc_invalid_op+0x1a/0x20 ? irq_work_claim+0x1e/0x40 ? intel_pmu_handle_irq+0x285/0x370 perf_event_nmi_handler+0x3d/0x60 nmi_handle+0x104/0x330 Thanks to Thomas Gleixner's analysis, the issue is caused by the low initial period (1) of the frequency estimation algorithm, which triggers the defects of the HW, specifically erratum HSW11 and HSW143. (For the details, please refer https://lore.kernel.org/lkml/87plq9l5d2.ffs@tglx/) The HSW11 requires a period larger than 100 for the INST_RETIRED.ALL event, but the initial period in the freq mode is 1. The erratum is the same as the BDM11, which has been supported in the kernel. A minimum period of 128 is enforced as well on HSW. HSW143 is regarding that the fixed counter 1 may overcount 32 with the Hyper-Threading is enabled. However, based on the test, the hardware has more issues than it tells. Besides the fixed counter 1, the message 'interrupt took too long' can be observed on any counter which was armed with a period < 32 and two events expired in the same NMI. A minimum period of 32 is enforced for the rest of the events. The recommended workaround code of the HSW143 is not implemented. Because it only addresses the issue for the fixed counter. It brings extra overhead through extra MSR writing. No related overcounting issue has been reported so far. Fixes: 3a632cb229bf ("perf/x86/intel: Add simple Haswell PMU support") Reported-by: Li Huafei <lihuafei1@huawei.com> Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20240819183004.3132920-1-kan.liang@linux.intel.com Closes: https://lore.kernel.org/lkml/20240729223328.327835-1-lihuafei1@huawei.com/
2024-08-05perf/x86/intel/bts: Fix comment about default perf_event_paranoid settingJames Clark
The default paranoid setting was updated in commit 0161028b7c8a ("perf/core: Change the default paranoia level to 2") so this comment is no longer true. Signed-off-by: James Clark <james.clark@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20240802105256.335961-1-james.clark@linaro.org
2024-08-05perf/x86/intel/uncore: Use D0:F0 as a default deviceZhenyu Wang
Some uncore PMON registers are located in the MMIO space of the Host Bridge and DRAM Controller device, which is located at D0:F0 for Tiger Lake and later client generation. Use D0:F0 as a default device. So it doesn't need to keep adding the complete Device ID list for each generation anymore. Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lore.kernel.org/r/20240731141353.759643-5-kan.liang@linux.intel.com
2024-08-05perf/x86/intel/uncore: Add LNL uncore iMC freerunning supportZhenyu Wang
LNL uncore imc freerunning counters keep same as previous HW. Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lore.kernel.org/r/20240731141353.759643-4-kan.liang@linux.intel.com
2024-08-05perf/x86/intel/uncore: Add Lunar Lake supportKan Liang
The uncore subsystem for Lunar Lake is similar to the previous Meteor Lake. The uncore PerfMon registers are located at both MSR and MMIO space. The ARB and iMC are kept. There is no difference from the Meteor Lake. Move the global control initialization to the first box of the CBOX. The sNCU is moved to the MMIO space. The HBO is newly added and only be accessed from the MMIO space. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240731141353.759643-3-kan.liang@linux.intel.com
2024-08-05perf/x86/intel/uncore: Factor out common MMIO init and ops functionsKan Liang
Some uncore PMON registers are located in the MMIO space. For the client machine, the MMIO space is usually located at D0:F0 but in a different BAR. For example, some uncore PMON registers are located in the SAF BAR, not the MCHBAR in the Lunar Lake. The current __uncore_imc_init_box() hard code the BAR information. Factor out the uncore_get_box_mmio_addr() which uses the BAR information as a parameter. The only change is the error output message. The hardcode name 'MCHBAR' is replaced by the offset of a BAR. Add a new macro, MMIO_UNCORE_COMMON_OPS(), since the MMIO ops functions are usually the same among different generations. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240731141353.759643-2-kan.liang@linux.intel.com
2024-08-05perf/x86/intel/uncore: Add Arrow Lake supportKan Liang
>From the perspective of the uncore PMU, the Arrow Lake is the same as the previous Meteor Lake. The only difference is the event list, which will be supported in the perf tool later. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240731141353.759643-1-kan.liang@linux.intel.com
2024-08-02perf,x86: avoid missing caller address in stack traces captured in uprobeAndrii Nakryiko
When tracing user functions with uprobe functionality, it's common to install the probe (e.g., a BPF program) at the first instruction of the function. This is often going to be `push %rbp` instruction in function preamble, which means that within that function frame pointer hasn't been established yet. This leads to consistently missing an actual caller of the traced function, because perf_callchain_user() only records current IP (capturing traced function) and then following frame pointer chain (which would be caller's frame, containing the address of caller's caller). So when we have target_1 -> target_2 -> target_3 call chain and we are tracing an entry to target_3, captured stack trace will report target_1 -> target_3 call chain, which is wrong and confusing. This patch proposes a x86-64-specific heuristic to detect `push %rbp` (`push %ebp` on 32-bit architecture) instruction being traced. Given entire kernel implementation of user space stack trace capturing works under assumption that user space code was compiled with frame pointer register (%rbp/%ebp) preservation, it seems pretty reasonable to use this instruction as a strong indicator that this is the entry to the function. In that case, return address is still pointed to by %rsp/%esp, so we fetch it and add to stack trace before proceeding to unwind the rest using frame pointer-based logic. We also check for `endbr64` (for 64-bit modes) as another common pattern for function entry, as suggested by Josh Poimboeuf. Even if we get this wrong sometimes for uprobes attached not at the function entry, it's OK because stack trace will still be overall meaningful, just with one extra bogus entry. If we don't detect this, we end up with guaranteed to be missing caller function entry in the stack trace, which is worse overall. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20240729175223.23914-1-andrii@kernel.org
2024-07-31perf/x86: Fix smp_processor_id()-in-preemptible warningsLi Huafei
The following bug was triggered on a system built with CONFIG_DEBUG_PREEMPT=y: # echo p > /proc/sysrq-trigger BUG: using smp_processor_id() in preemptible [00000000] code: sh/117 caller is perf_event_print_debug+0x1a/0x4c0 CPU: 3 UID: 0 PID: 117 Comm: sh Not tainted 6.11.0-rc1 #109 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x4f/0x60 check_preemption_disabled+0xc8/0xd0 perf_event_print_debug+0x1a/0x4c0 __handle_sysrq+0x140/0x180 write_sysrq_trigger+0x61/0x70 proc_reg_write+0x4e/0x70 vfs_write+0xd0/0x430 ? handle_mm_fault+0xc8/0x240 ksys_write+0x9c/0xd0 do_syscall_64+0x96/0x190 entry_SYSCALL_64_after_hwframe+0x4b/0x53 This is because the commit d4b294bf84db ("perf/x86: Hybrid PMU support for counters") took smp_processor_id() outside the irq critical section. If a preemption occurs in perf_event_print_debug() and the task is migrated to another cpu, we may get incorrect pmu debug information. Move smp_processor_id() back inside the irq critical section to fix this issue. Fixes: d4b294bf84db ("perf/x86: Hybrid PMU support for counters") Signed-off-by: Li Huafei <lihuafei1@huawei.com> Reviewed-and-tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lore.kernel.org/r/20240729220928.325449-1-lihuafei1@huawei.com
2024-07-29perf/x86: Add hw_perf_event::aux_configPeter Zijlstra
Start a new section for AUX PMUs in hw_perf_event. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2024-07-29perf/x86/intel/pt: Fix sampling synchronizationAdrian Hunter
pt_event_snapshot_aux() uses pt->handle_nmi to determine if tracing needs to be stopped, however tracing can still be going because pt->handle_nmi is set to zero before tracing is stopped in pt_event_stop, whereas pt_event_snapshot_aux() requires that tracing must be stopped in order to copy a sample of trace from the buffer. Instead call pt_config_stop() always, which anyway checks config for RTIT_CTL_TRACEEN and does nothing if it is already clear. Note pt_event_snapshot_aux() can continue to use pt->handle_nmi to determine if the trace needs to be restarted afterwards. Fixes: 25e8920b301c ("perf/x86/intel/pt: Add sampling support") Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20240715160712.127117-2-adrian.hunter@intel.com
2024-07-29perf/x86/intel/cstate: Add pkg C2 residency counter for Sierra ForestZhenyu Wang
Package C2 residency counter is also available on Sierra Forest. So add it support in srf_cstates. Fixes: 3877d55a0db2 ("perf/x86/intel/cstate: Add Sierra Forest support") Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kan Liang <kan.liang@linux.intel.com> Tested-by: Wendy Wang <wendy.wang@intel.com> Link: https://lore.kernel.org/r/20240717031609.74513-1-zhenyuw@linux.intel.com
2024-07-16Merge tag 'perf-core-2024-07-16' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull performance events updates from Ingo Molnar: - Intel PT support enhancements & fixes - Fix leaked SIGTRAP events - Improve and fix the Intel uncore driver - Add support for Intel HBM and CXL uncore counters - Add Intel Lake and Arrow Lake support - AMD uncore driver fixes - Make SIGTRAP and __perf_pending_irq() work on RT - Micro-optimizations - Misc cleanups and fixes * tag 'perf-core-2024-07-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits) perf/x86/intel: Add a distinct name for Granite Rapids perf/x86/intel/ds: Fix non 0 retire latency on Raptorlake perf/x86/intel: Hide Topdown metrics events if the feature is not enumerated perf/x86/intel/uncore: Fix the bits of the CHA extended umask for SPR perf: Split __perf_pending_irq() out of perf_pending_irq() perf: Don't disable preemption in perf_pending_task(). perf: Move swevent_htable::recursion into task_struct. perf: Shrink the size of the recursion counter. perf: Enqueue SIGTRAP always via task_work. task_work: Add TWA_NMI_CURRENT as an additional notify mode. perf: Move irq_work_queue() where the event is prepared. perf: Fix event leak upon exec and file release perf: Fix event leak upon exit task_work: Introduce task_work_cancel() again task_work: s/task_work_cancel()/task_work_cancel_func()/ perf/x86/amd/uncore: Fix DF and UMC domain identification perf/x86/amd/uncore: Avoid PMU registration if counters are unavailable perf/x86/intel: Support Perfmon MSRs aliasing perf/x86/intel: Support PERFEVTSEL extension perf/x86: Add config_mask to represent EVENTSEL bitmask ...
2024-07-16Merge tag 'locking-core-2024-07-15' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: - Jump label fixes, including a perf events fix that originally manifested as jump label failures, but was a serialization bug at the usage site - Mark down_write*() helpers as __always_inline, to improve WCHAN debuggability - Misc cleanups and fixes * tag 'locking-core-2024-07-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/rwsem: Add __always_inline annotation to __down_write_common() and inlined callers jump_label: Simplify and clarify static_key_fast_inc_cpus_locked() jump_label: Clarify condition in static_key_fast_inc_not_disabled() jump_label: Fix concurrency issues in static_key_slow_dec() perf/x86: Serialize set_attr_rdpmc() cleanup: Standardize the header guard define's name
2024-07-15Merge tag 'x86_cpu_for_v6.11_rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 cpu model updates from Borislav Petkov: - Flip the logic to add feature names to /proc/cpuinfo to having to explicitly specify the flag if there's a valid reason to show it in /proc/cpuinfo - Switch a bunch of Intel x86 model checking code to the new CPU model defines - Fixes and cleanups * tag 'x86_cpu_for_v6.11_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/cpu/intel: Drop stray FAM6 check with new Intel CPU model defines x86/cpufeatures: Flip the /proc/cpuinfo appearance logic x86/CPU/AMD: Always inline amd_clear_divider() x86/mce/inject: Add missing MODULE_DESCRIPTION() line perf/x86/rapl: Switch to new Intel CPU model defines x86/boot: Switch to new Intel CPU model defines x86/cpu: Switch to new Intel CPU model defines perf/x86/intel: Switch to new Intel CPU model defines x86/virt/tdx: Switch to new Intel CPU model defines x86/PCI: Switch to new Intel CPU model defines x86/cpu/intel: Switch to new Intel CPU model defines x86/platform/intel-mid: Switch to new Intel CPU model defines x86/pconfig: Remove unused MKTME pconfig code x86/cpu: Remove useless work in detect_tme_early()
2024-07-09perf/x86/intel: Add a distinct name for Granite RapidsKan Liang
Currently, the Sapphire Rapids and Granite Rapids share the same PMU name, sapphire_rapids. Because from the kernel’s perspective, GNR is similar to SPR. The only key difference is that they support different extra MSRs. The code path and the PMU name are shared. However, from end users' perspective, they are quite different. Besides the extra MSRs, GNR has a newer PEBS format, supports Retire Latency, supports new CPUID enumeration architecture, doesn't required the load-latency AUX event, has additional TMA Level 1 Architectural Events, etc. The differences can be enumerated by CPUID or the PERF_CAPABILITIES MSR. They weren't reflected in the model-specific kernel setup. But it is worth to have a distinct PMU name for GNR. Fixes: a6742cb90b56 ("perf/x86/intel: Fix the FRONTEND encoding on GNR and MTL") Suggested-by: Ahmad Yasin <ahmad.yasin@intel.com> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20240708193336.1192217-3-kan.liang@linux.intel.com
2024-07-09perf/x86/intel/ds: Fix non 0 retire latency on RaptorlakeKan Liang
A non-0 retire latency can be observed on a Raptorlake which doesn't support the retire latency feature. By design, the retire latency shares the PERF_SAMPLE_WEIGHT_STRUCT sample type with other types of latency. That could avoid adding too many different sample types to support all kinds of latency. For the machine which doesn't support some kind of latency, 0 should be returned. Perf doesn’t clear/init all the fields of a sample data for the sake of performance. It expects the later perf_{prepare,output}_sample() to update the uninitialized field. However, the current implementation doesn't touch the field of the retire latency if the feature is not supported. The memory garbage is dumped into the perf data. Clear the retire latency if the feature is not supported. Fixes: c87a31093c70 ("perf/x86: Support Retire Latency") Reported-by: "Bayduraev, Alexey V" <alexey.v.bayduraev@intel.com> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: "Bayduraev, Alexey V" <alexey.v.bayduraev@intel.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20240708193336.1192217-4-kan.liang@linux.intel.com
2024-07-09perf/x86/intel: Hide Topdown metrics events if the feature is not enumeratedKan Liang
The below error is observed on Ice Lake VM. $ perf stat Error: The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (slots). /bin/dmesg | grep -i perf may provide additional information. In a virtualization env, the Topdown metrics and the slots event haven't been supported yet. The guest CPUID doesn't enumerate them. However, the current kernel unconditionally exposes the slots event and the Topdown metrics events to sysfs, which misleads the perf tool and triggers the error. Hide the perf-metrics topdown events and the slots event if the perf-metrics feature is not enumerated. The big core of a hybrid platform can also supports the perf-metrics feature. Fix the hybrid platform as well. Closes: https://lore.kernel.org/lkml/CAM9d7cj8z+ryyzUHR+P1Dcpot2jjW+Qcc4CPQpfafTXN=LEU0Q@mail.gmail.com/ Reported-by: Dongli Zhang <dongli.zhang@oracle.com> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Dongli Zhang <dongli.zhang@oracle.com> Link: https://lkml.kernel.org/r/20240708193336.1192217-2-kan.liang@linux.intel.com
2024-07-09perf/x86/intel/uncore: Fix the bits of the CHA extended umask for SPRKan Liang
The perf stat errors out with UNC_CHA_TOR_INSERTS.IA_HIT_CXL_ACC_LOCAL event. $perf stat -e uncore_cha_55/event=0x35,umask=0x10c0008101/ -a -- ls event syntax error: '..0x35,umask=0x10c0008101/' \___ Bad event or PMU The definition of the CHA umask is config:8-15,32-55, which is 32bit. However, the umask of the event is bigger than 32bit. This is an error in the original uncore spec. Add a new umask_ext5 for the new CHA umask range. Fixes: 949b11381f81 ("perf/x86/intel/uncore: Add Sapphire Rapids server CHA support") Closes: https://lore.kernel.org/linux-perf-users/alpine.LRH.2.20.2401300733310.11354@Diego/ Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ian Rogers <irogers@google.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20240708185524.1185505-1-kan.liang@linux.intel.com
2024-07-04perf/x86/amd/uncore: Fix DF and UMC domain identificationSandipan Das
For uncore PMUs, a single context is shared across all CPUs in a domain. The domain can be a CCX, like in the case of the L3 PMU, or a socket, like in the case of DF and UMC PMUs. This information is available via the PMU's cpumask. For contexts shared across a socket, the domain is currently determined from topology_die_id() which is incorrect after the introduction of commit 63edbaa48a57 ("x86/cpu/topology: Add support for the AMD 0x80000026 leaf") as it now returns a CCX identifier on Zen 4 and later systems which support CPUID leaf 0x80000026. Use topology_logical_package_id() instead as it always returns a socket identifier irrespective of the availability of CPUID leaf 0x80000026. Fixes: 63edbaa48a57 ("x86/cpu/topology: Add support for the AMD 0x80000026 leaf") Signed-off-by: Sandipan Das <sandipan.das@amd.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20240626074942.1044818-1-sandipan.das@amd.com
2024-07-04perf/x86/amd/uncore: Avoid PMU registration if counters are unavailableSandipan Das
X86_FEATURE_PERFCTR_NB and X86_FEATURE_PERFCTR_LLC are derived from CPUID leaf 0x80000001 ECX bits 24 and 28 respectively and denote the availability of DF and L3 counters. When these bits are not set, the corresponding PMUs have no counters and hence, should not be registered. Fixes: 07888daa056e ("perf/x86/amd/uncore: Move discovery and registration") Signed-off-by: Sandipan Das <sandipan.das@amd.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20240626074404.1044230-1-sandipan.das@amd.com
2024-07-04perf/x86/intel: Support Perfmon MSRs aliasingKan Liang
The architectural performance monitoring V6 supports a new range of counters' MSRs in the 19xxH address range. They include all the GP counter MSRs, the GP control MSRs, and the fixed counter MSRs. The step between each sibling counter is 4. Add intel_pmu_addr_offset() to calculate the correct offset. Add fixedctr in struct x86_pmu to store the address of the fixed counter 0. It can be used to calculate the rest of the fixed counters. The MSR address of the fixed counter control is not changed. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Ian Rogers <irogers@google.com> Link: https://lkml.kernel.org/r/20240626143545.480761-9-kan.liang@linux.intel.com
2024-07-04perf/x86/intel: Support PERFEVTSEL extensionKan Liang
Two new fields (the unit mask2, and the equal flag) are added in the IA32_PERFEVTSELx MSRs. They can be enumerated by the CPUID.23H.0.EBX. Update the config_mask in x86_pmu and x86_hybrid_pmu for the true layout of the PERFEVTSEL. Expose the new formats into sysfs if they are available. The umask extension reuses the same format attr name "umask" as the previous umask. Add umask2_show to determine/display the correct format for the current machine. Co-developed-by: Dapeng Mi <dapeng1.mi@linux.intel.com> Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Ian Rogers <irogers@google.com> Link: https://lkml.kernel.org/r/20240626143545.480761-8-kan.liang@linux.intel.com
2024-07-04perf/x86: Add config_mask to represent EVENTSEL bitmaskKan Liang
Different vendors may support different fields in EVENTSEL MSR, such as Intel would introduce new fields umask2 and eq bits in EVENTSEL MSR since Perfmon version 6. However, a fixed mask X86_RAW_EVENT_MASK is used to filter the attr.config. Introduce a new config_mask to record the real supported EVENTSEL bitmask. Only apply it to the existing code now. No functional change. Co-developed-by: Dapeng Mi <dapeng1.mi@linux.intel.com> Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Ian Rogers <irogers@google.com> Link: https://lkml.kernel.org/r/20240626143545.480761-7-kan.liang@linux.intel.com
2024-07-04perf/x86/intel: Support new data source for Lunar LakeKan Liang
A new PEBS data source format is introduced for the p-core of Lunar Lake. The data source field is extended to 8 bits with new encodings. A new layout is introduced into the union intel_x86_pebs_dse. Introduce the lnl_latency_data() to parse the new format. Enlarge the pebs_data_source[] accordingly to include new encodings. Only the mem load and the mem store events can generate the data source. Introduce INTEL_HYBRID_LDLAT_CONSTRAINT and INTEL_HYBRID_STLAT_CONSTRAINT to mark them. Add two new bits for the new cache-related data src, L2_MHB and MSC. The L2_MHB is short for L2 Miss Handling Buffer, which is similar to LFB (Line Fill Buffer), but to track the L2 Cache misses. The MSC stands for the memory-side cache. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Ian Rogers <irogers@google.com> Link: https://lkml.kernel.org/r/20240626143545.480761-6-kan.liang@linux.intel.com
2024-07-04perf/x86/intel: Rename model-specific pebs_latency_data functionsKan Liang
The model-specific pebs_latency_data functions of ADL and MTL use the "small" as a postfix to indicate the e-core. The postfix is too generic for a model-specific function. It cannot provide useful information that can directly map it to a specific uarch, which can facilitate the development and maintenance. Use the abbr of the uarch to rename the model-specific functions. Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ian Rogers <irogers@google.com> Link: https://lkml.kernel.org/r/20240626143545.480761-5-kan.liang@linux.intel.com
2024-07-04perf/x86: Add Lunar Lake and Arrow Lake supportKan Liang
From PMU's perspective, Lunar Lake and Arrow Lake are similar to the previous generation Meteor Lake. Both are hybrid platforms, with e-core and p-core. The key differences include: - The e-core supports 3 new fixed counters - The p-core supports an updated PEBS Data Source format - More GP counters (Updated event constraint table) - New Architectural performance monitoring V6 (New Perfmon MSRs aliasing, umask2, eq). - New PEBS format V6 (Counters Snapshotting group) - New RDPMC metrics clear mode The legacy features, the 3 new fixed counters and updated event constraint table are enabled in this patch. The new PEBS data source format, the architectural performance monitoring V6, the PEBS format V6, and the new RDPMC metrics clear mode are supported in the following patches. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Ian Rogers <irogers@google.com> Link: https://lkml.kernel.org/r/20240626143545.480761-4-kan.liang@linux.intel.com
2024-07-04perf/x86: Support counter maskKan Liang
The current perf assumes that both GP and fixed counters are contiguous. But it's not guaranteed on newer Intel platforms or in a virtualization environment. Use the counter mask to replace the number of counters for both GP and the fixed counters. For the other ARCHs or old platforms which don't support a counter mask, using GENMASK_ULL(num_counter - 1, 0) to replace. There is no functional change for them. The interface to KVM is not changed. The number of counters still be passed to KVM. It can be updated later separately. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Ian Rogers <irogers@google.com> Link: https://lkml.kernel.org/r/20240626143545.480761-3-kan.liang@linux.intel.com
2024-07-04perf/x86/intel: Support the PEBS event maskKan Liang
The current perf assumes that the counters that support PEBS are contiguous. But it's not guaranteed with the new leaf 0x23 introduced. The counters are enumerated with a counter mask. There may be holes in the counter mask for future platforms or in a virtualization environment. Store the PEBS event mask rather than the maximum number of PEBS counters in the x86 PMU structures. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Ian Rogers <irogers@google.com> Link: https://lkml.kernel.org/r/20240626143545.480761-2-kan.liang@linux.intel.com
2024-07-04perf/x86/intel/cstate: Add Lunarlake supportZhang Rui
Compared with previous client platforms, PC8 is removed from Lunarlake. It supports CC1/CC6/CC7 and PC2/PC3/PC6/PC10 residency counters. Signed-off-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lore.kernel.org/r/20240628031758.43103-4-rui.zhang@intel.com
2024-07-04perf/x86/intel/cstate: Add Arrowlake supportZhang Rui
Like Alderlake, Arrowlake supports CC1/CC6/CC7 and PC2/PC3/PC6/PC8/PC10. Signed-off-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lore.kernel.org/r/20240628031758.43103-3-rui.zhang@intel.com
2024-07-04perf/x86/intel/cstate: Fix Alderlake/Raptorlake/MeteorlakeZhang Rui
For Alderlake, the spec changes after the patch submitted and PC7/PC9 are removed. Raptorlake and Meteorlake, which copy the Alderlake cstate PMU, also don't have PC7/PC9. Remove PC7/PC9 support for Alderlake/Raptorlake/Meteorlake. Fixes: d0ca946bcf84 ("perf/x86/cstate: Add Alder Lake CPU support") Signed-off-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lore.kernel.org/r/20240628031758.43103-2-rui.zhang@intel.com
2024-07-04Merge branch 'tip/x86/cpu'Peter Zijlstra
The Lunarlake patches rely on the new VFM stuff. Signed-off-by: Peter Zijlstra <peterz@infradead.org>
2024-07-04perf/x86/intel/pt: Fix pt_topa_entry_for_page() address calculationAdrian Hunter
Currently, perf allocates an array of page pointers which is limited in size by MAX_PAGE_ORDER. That in turn limits the maximum Intel PT buffer size to 2GiB. Should that limitation be lifted, the Intel PT driver can support larger sizes, except for one calculation in pt_topa_entry_for_page(), which is limited to 32-bits. Fix pt_topa_entry_for_page() address calculation by adding a cast. Fixes: 39152ee51b77 ("perf/x86/intel/pt: Get rid of reverse lookup table for ToPA") Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240624201101.60186-4-adrian.hunter@intel.com
2024-07-04perf/x86/intel/pt: Fix a topa_entry base address calculationAdrian Hunter
topa_entry->base is a bit-field. Bit-fields are not promoted to a 64-bit type, even if the underlying type is 64-bit, and so, if necessary, must be cast to a larger type when calculations are done. Fix a topa_entry->base address calculation by adding a cast. Without the cast, the address was limited to 36-bits i.e. 64GiB. The address calculation is used on systems that do not support Multiple Entry ToPA (only Broadwell), and affects physical addresses on or above 64GiB. Instead of writing to the correct address, the address comprising the first 36 bits would be written to. Intel PT snapshot and sampling modes are not affected. Fixes: 52ca9ced3f70 ("perf/x86/intel/pt: Add Intel PT PMU driver") Reported-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240624201101.60186-3-adrian.hunter@intel.com
2024-07-04perf/x86/intel/pt: Fix topa_entry base lengthMarco Cavenati
topa_entry->base needs to store a pfn. It obviously needs to be large enough to store the largest possible x86 pfn which is MAXPHYADDR-PAGE_SIZE (52-12). So it is 4 bits too small. Increase the size of topa_entry->base from 36 bits to 40 bits. Note, systems where physical addresses can be 256TiB or more are affected. [ Adrian: Amend commit message as suggested by Dave Hansen ] Fixes: 52ca9ced3f70 ("perf/x86/intel/pt: Add Intel PT PMU driver") Signed-off-by: Marco Cavenati <cavenati.marco@gmail.com> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Adrian Hunter <adrian.hunter@intel.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240624201101.60186-2-adrian.hunter@intel.com
2024-06-17perf/x86/intel/uncore: Support HBM and CXL PMON countersKan Liang
Unknown uncore PMON types can be found in both SPR and EMR with HBM or CXL. $ls /sys/devices/ | grep type uncore_type_12_16 uncore_type_12_18 uncore_type_12_2 uncore_type_12_4 uncore_type_12_6 uncore_type_12_8 uncore_type_13_17 uncore_type_13_19 uncore_type_13_3 uncore_type_13_5 uncore_type_13_7 uncore_type_13_9 The unknown PMON types are HBM and CXL PMON. Except for the name, the other information regarding the HBM and CXL PMON counters can be retrieved via the discovery table. Add them into the uncores tables for SPR and EMR. The event config registers for all CXL related units are 8-byte apart. Add SPR_UNCORE_MMIO_OFFS8_COMMON_FORMAT to specially handle it. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Yunying Sun <yunying.sun@intel.com> Link: https://lore.kernel.org/r/20240614134631.1092359-9-kan.liang@linux.intel.com
2024-06-17perf/x86/uncore: Cleanup unused unit structureKan Liang
The unit control and ID information are retrieved from the unit control RB tree. No one uses the old structure anymore. Remove them. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Yunying Sun <yunying.sun@intel.com> Link: https://lore.kernel.org/r/20240614134631.1092359-8-kan.liang@linux.intel.com
2024-06-17perf/x86/uncore: Apply the unit control RB tree to PCI uncore unitsKan Liang
The unit control RB tree has the unit control and unit ID information for all the PCI units. Use them to replace the box_ctls/pci_offsets to get an accurate unit control address for PCI uncore units. The UPI/M3UPI units in the discovery table are ignored. Please see the commit 65248a9a9ee1 ("perf/x86/uncore: Add a quirk for UPI on SPR"). Manually allocate a unit control RB tree for UPI/M3UPI. Add cleanup_extra_boxes to release such manual allocation. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Yunying Sun <yunying.sun@intel.com> Link: https://lore.kernel.org/r/20240614134631.1092359-7-kan.liang@linux.intel.com
2024-06-17perf/x86/uncore: Apply the unit control RB tree to MSR uncore unitsKan Liang
The unit control RB tree has the unit control and unit ID information for all the MSR units. Use them to replace the box_ctl and uncore_msr_box_ctl() to get an accurate unit control address for MSR uncore units. Add intel_generic_uncore_assign_hw_event(), which utilizes the accurate unit control address from the unit control RB tree to calculate the config_base and event_base. The unit id related information should be retrieved from the unit control RB tree as well. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Yunying Sun <yunying.sun@intel.com> Link: https://lore.kernel.org/r/20240614134631.1092359-6-kan.liang@linux.intel.com
2024-06-17perf/x86/uncore: Apply the unit control RB tree to MMIO uncore unitsKan Liang
The unit control RB tree has the unit control and unit ID information for all the units. Use it to replace the box_ctls/mmio_offsets to get an accurate unit control address for MMIO uncore units. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Yunying Sun <yunying.sun@intel.com> Link: https://lore.kernel.org/r/20240614134631.1092359-5-kan.liang@linux.intel.com
2024-06-17perf/x86/uncore: Retrieve the unit ID from the unit control RB treeKan Liang
The box_ids only save the unit ID for the first die. If a unit, e.g., a CXL unit, doesn't exist in the first die. The unit ID cannot be retrieved. The unit control RB tree also stores the unit ID information. Retrieve the unit ID from the unit control RB tree Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Yunying Sun <yunying.sun@intel.com> Link: https://lore.kernel.org/r/20240614134631.1092359-4-kan.liang@linux.intel.com
2024-06-17perf/x86/uncore: Support per PMU cpumaskKan Liang
The cpumask of some uncore units, e.g., CXL uncore units, may be wrong under some configurations. Perf may access an uncore counter of a non-existent uncore unit. The uncore driver assumes that all uncore units are symmetric among dies. A global cpumask is shared among all uncore PMUs. However, some CXL uncore units may only be available on some dies. A per PMU cpumask is introduced to track the CPU mask of this PMU. The driver searches the unit control RB tree to check whether the PMU is available on a given die, and updates the per PMU cpumask accordingly. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Yunying Sun <yunying.sun@intel.com> Link: https://lore.kernel.org/r/20240614134631.1092359-3-kan.liang@linux.intel.com
2024-06-17perf/x86/uncore: Save the unit control address of all unitsKan Liang
The unit control address of some CXL units may be wrongly calculated under some configuration on a EMR machine. The current implementation only saves the unit control address of the units from the first die, and the first unit of the rest of dies. Perf assumed that the units from the other dies have the same offset as the first die. So the unit control address of the rest of the units can be calculated. However, the assumption is wrong, especially for the CXL units. Introduce an RB tree for each uncore type to save the unit control address and three kinds of ID information (unit ID, PMU ID, and die ID) for all units. The unit ID is a physical ID of a unit. The PMU ID is a logical ID assigned to a unit. The logical IDs start from 0 and must be contiguous. The physical ID and the logical ID are 1:1 mapping. The units with the same physical ID in different dies share the same PMU. The die ID indicates which die a unit belongs to. The RB tree can be searched by two different keys (unit ID or PMU ID + die ID). During the RB tree setup, the unit ID is used as a key to look up the RB tree. The perf can create/assign a proper PMU ID to the unit. Later, after the RB tree is setup, PMU ID + die ID is used as a key to look up the RB tree to fill the cpumask of a PMU. It's used more frequently, so PMU ID + die ID is compared in the unit_less(). The uncore_find_unit() has to be O(N). But the RB tree setup only occurs once during the driver load time. It should be acceptable. Compared with the current implementation, more space is required to save the information of all units. The extra size should be acceptable. For example, on EMR, there are 221 units at most. For a 2-socket machine, the extra space is ~6KB at most. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240614134631.1092359-2-kan.liang@linux.intel.com