diff options
author | Martin Hicks <mort@sgi.com> | 2005-06-21 17:14:41 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-06-21 18:46:14 -0700 |
commit | 753ee728964e5afb80c17659cc6c3a6fd0a42fe0 (patch) | |
tree | 41c9a7700d0858c1f77c5bdaba97e5b636f69b06 /mm/vmscan.c | |
parent | bfbb38fb808ac23ef44472d05d9bb36edfb49ed0 (diff) |
[PATCH] VM: early zone reclaim
This is the core of the (much simplified) early reclaim. The goal of this
patch is to reclaim some easily-freed pages from a zone before falling back
onto another zone.
One of the major uses of this is NUMA machines. With the default allocator
behavior the allocator would look for memory in another zone, which might be
off-node, before trying to reclaim from the current zone.
This adds a zone tuneable to enable early zone reclaim. It is selected on a
per-zone basis and is turned on/off via syscall.
Adding some extra throttling on the reclaim was also required (patch
4/4). Without the machine would grind to a crawl when doing a "make -j"
kernel build. Even with this patch the System Time is higher on
average, but it seems tolerable. Here are some numbers for kernbench
runs on a 2-node, 4cpu, 8Gig RAM Altix in the "make -j" run:
wall user sys %cpu ctx sw. sleeps
---- ---- --- ---- ------ ------
No patch 1009 1384 847 258 298170 504402
w/patch, no reclaim 880 1376 667 288 254064 396745
w/patch & reclaim 1079 1385 926 252 291625 548873
These numbers are the average of 2 runs of 3 "make -j" runs done right
after system boot. Run-to-run variability for "make -j" is huge, so
these numbers aren't terribly useful except to seee that with reclaim
the benchmark still finishes in a reasonable amount of time.
I also looked at the NUMA hit/miss stats for the "make -j" runs and the
reclaim doesn't make any difference when the machine is thrashing away.
Doing a "make -j8" on a single node that is filled with page cache pages
takes 700 seconds with reclaim turned on and 735 seconds without reclaim
(due to remote memory accesses).
The simple zone_reclaim syscall program is at
http://www.bork.org/~mort/sgi/zone_reclaim.c
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r-- | mm/vmscan.c | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index 6379ddbffd9b..7da846960d8a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1323,3 +1323,67 @@ static int __init kswapd_init(void) } module_init(kswapd_init) + + +/* + * Try to free up some pages from this zone through reclaim. + */ +int zone_reclaim(struct zone *zone, unsigned int gfp_mask, unsigned int order) +{ + struct scan_control sc; + int nr_pages = 1 << order; + int total_reclaimed = 0; + + /* The reclaim may sleep, so don't do it if sleep isn't allowed */ + if (!(gfp_mask & __GFP_WAIT)) + return 0; + if (zone->all_unreclaimable) + return 0; + + sc.gfp_mask = gfp_mask; + sc.may_writepage = 0; + sc.may_swap = 0; + sc.nr_mapped = read_page_state(nr_mapped); + sc.nr_scanned = 0; + sc.nr_reclaimed = 0; + /* scan at the highest priority */ + sc.priority = 0; + + if (nr_pages > SWAP_CLUSTER_MAX) + sc.swap_cluster_max = nr_pages; + else + sc.swap_cluster_max = SWAP_CLUSTER_MAX; + + shrink_zone(zone, &sc); + total_reclaimed = sc.nr_reclaimed; + + return total_reclaimed; +} + +asmlinkage long sys_set_zone_reclaim(unsigned int node, unsigned int zone, + unsigned int state) +{ + struct zone *z; + int i; + + if (node >= MAX_NUMNODES || !node_online(node)) + return -EINVAL; + + /* This will break if we ever add more zones */ + if (!(zone & (1<<ZONE_DMA|1<<ZONE_NORMAL|1<<ZONE_HIGHMEM))) + return -EINVAL; + + for (i = 0; i < MAX_NR_ZONES; i++) { + if (!(zone & 1<<i)) + continue; + + z = &NODE_DATA(node)->node_zones[i]; + + if (state) + z->reclaim_pages = 1; + else + z->reclaim_pages = 0; + } + + return 0; +} |