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| author |   Ming Lei <ming.lei@redhat.com> | 2019-07-25 17:41:46 +0800 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2019-08-04 21:43:12 -0600 |
| commit | 556f36e90dbe7dded81f4fac084d2bc8a2458330 (patch) | |
| tree | d8e04c7dfcdf85432ca737c35250a23091c869a2 | |
| parent | scsi: implement .cleanup_rq callback (diff) | |
| download | linux-dev-556f36e90dbe7dded81f4fac084d2bc8a2458330.tar.xz linux-dev-556f36e90dbe7dded81f4fac084d2bc8a2458330.zip | |
blk-mq: balance mapping between present CPUs and queues
Spread queues among present CPUs first, then building mapping on other
non-present CPUs.
So we can minimize count of dead queues which are mapped by un-present
CPUs only. Then bad IO performance can be avoided by unbalanced mapping
between present CPUs and queues.
The similar policy has been applied on Managed IRQ affinity.
Cc: Yi Zhang <yi.zhang@redhat.com>
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk-mq-cpumap.c | 29 |
1 files changed, 22 insertions, 7 deletions
diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c index f945621a0e8f..0157f2b3485a 100644 --- a/block/blk-mq-cpumap.c +++ b/block/blk-mq-cpumap.c @@ -15,10 +15,10 @@ #include "blk.h" #include "blk-mq.h" -static int cpu_to_queue_index(struct blk_mq_queue_map *qmap, - unsigned int nr_queues, const int cpu) +static int queue_index(struct blk_mq_queue_map *qmap, + unsigned int nr_queues, const int q) { - return qmap->queue_offset + (cpu % nr_queues); + return qmap->queue_offset + (q % nr_queues); } static int get_first_sibling(unsigned int cpu) @@ -36,21 +36,36 @@ int blk_mq_map_queues(struct blk_mq_queue_map *qmap) { unsigned int *map = qmap->mq_map; unsigned int nr_queues = qmap->nr_queues; - unsigned int cpu, first_sibling; + unsigned int cpu, first_sibling, q = 0; + + for_each_possible_cpu(cpu) + map[cpu] = -1; + + /* + * Spread queues among present CPUs first for minimizing + * count of dead queues which are mapped by all un-present CPUs + */ + for_each_present_cpu(cpu) { + if (q >= nr_queues) + break; + map[cpu] = queue_index(qmap, nr_queues, q++); + } for_each_possible_cpu(cpu) { + if (map[cpu] != -1) + continue; /* * First do sequential mapping between CPUs and queues. * In case we still have CPUs to map, and we have some number of * threads per cores then map sibling threads to the same queue * for performance optimizations. */ - if (cpu < nr_queues) { - map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu); + if (q < nr_queues) { + map[cpu] = queue_index(qmap, nr_queues, q++); } else { first_sibling = get_first_sibling(cpu); if (first_sibling == cpu) - map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu); + map[cpu] = queue_index(qmap, nr_queues, q++); else map[cpu] = map[first_sibling]; } |