diff options
| author | Ming Lei <ming.lei@redhat.com> | 2018-04-08 17:48:09 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2018-04-10 08:38:46 -0600 |
| commit | 476f8c98a9bccccbb97866974ffc80879adf2bbb (patch) | |
| tree | 2c8163291812b7d1b54790b5ccb57f4f91cb44bf | |
| parent | bffa9909a6b48d8ca3398dec601bc9162a4020c4 (diff) | |
blk-mq: avoid to write intermediate result to hctx->next_cpu
This patch figures out the final selected CPU, then writes
it to hctx->next_cpu once, then we can avoid to intermediate
next cpu observed from other dispatch paths.
Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk-mq.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index f489ec920807..db178c577068 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1344,26 +1344,24 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx) { bool tried = false; + int next_cpu = hctx->next_cpu; if (hctx->queue->nr_hw_queues == 1) return WORK_CPU_UNBOUND; if (--hctx->next_cpu_batch <= 0) { - int next_cpu; select_cpu: - next_cpu = cpumask_next_and(hctx->next_cpu, hctx->cpumask, + next_cpu = cpumask_next_and(next_cpu, hctx->cpumask, cpu_online_mask); if (next_cpu >= nr_cpu_ids) - next_cpu = cpumask_first_and(hctx->cpumask,cpu_online_mask); + next_cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask); /* * No online CPU is found, so have to make sure hctx->next_cpu * is set correctly for not breaking workqueue. */ if (next_cpu >= nr_cpu_ids) - hctx->next_cpu = cpumask_first(hctx->cpumask); - else - hctx->next_cpu = next_cpu; + next_cpu = cpumask_first(hctx->cpumask); hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH; } @@ -1371,7 +1369,7 @@ select_cpu: * Do unbound schedule if we can't find a online CPU for this hctx, * and it should only happen in the path of handling CPU DEAD. */ - if (!cpu_online(hctx->next_cpu)) { + if (!cpu_online(next_cpu)) { if (!tried) { tried = true; goto select_cpu; @@ -1381,10 +1379,13 @@ select_cpu: * Make sure to re-select CPU next time once after CPUs * in hctx->cpumask become online again. */ + hctx->next_cpu = next_cpu; hctx->next_cpu_batch = 1; return WORK_CPU_UNBOUND; } - return hctx->next_cpu; + + hctx->next_cpu = next_cpu; + return next_cpu; } static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async, |