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| author | Pavel Begunkov <asml.silence@gmail.com> | 2024-02-07 14:14:29 +0000 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2024-02-08 10:18:48 -0700 |
| commit | e516c3fc6c182736aec5418a73f15199640491e2 (patch) | |
| tree | 10bc35f89a0830ed0f4c288bcb82d253b4f2bb81 /block | |
| parent | c9f5f3aa19c617fe85085b19abbf7a9a077336d0 (diff) | |
| download | linux-e516c3fc6c182736aec5418a73f15199640491e2.tar.gz linux-e516c3fc6c182736aec5418a73f15199640491e2.tar.bz2 linux-e516c3fc6c182736aec5418a73f15199640491e2.zip | |
block: optimise in irq bio put caching
When enlisting a bio into ->free_list_irq we protect the list by
disabling irqs. It's likely they're already disabled and performance of
local_irq_{save,restore}() is decent, but it's not zero cost.
Let's only use the irq cache when when we're serving a hard irq, which
allows to remove local_irq_{save,restore}(), and fall back to bio_free()
in all left cases.
Profiles indicate that the bio_put() cost is reduced by ~3.5 times
(1.76% -> 0.49%), and total throughput of a CPU bound benchmark improve
by around 1% (t/io_uring with high QD and several drives).
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/36d207540b7046c653cc16e5ff08fe7234b19f81.1707314970.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/bio.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/block/bio.c b/block/bio.c index 8da941974f88..00847ff1415c 100644 --- a/block/bio.c +++ b/block/bio.c @@ -762,30 +762,31 @@ static inline void bio_put_percpu_cache(struct bio *bio) struct bio_alloc_cache *cache; cache = per_cpu_ptr(bio->bi_pool->cache, get_cpu()); - if (READ_ONCE(cache->nr_irq) + cache->nr > ALLOC_CACHE_MAX) { - put_cpu(); - bio_free(bio); - return; - } - - bio_uninit(bio); + if (READ_ONCE(cache->nr_irq) + cache->nr > ALLOC_CACHE_MAX) + goto out_free; if (in_task()) { + bio_uninit(bio); bio->bi_next = cache->free_list; /* Not necessary but helps not to iopoll already freed bios */ bio->bi_bdev = NULL; cache->free_list = bio; cache->nr++; - } else { - unsigned long flags; + } else if (in_hardirq()) { + lockdep_assert_irqs_disabled(); - local_irq_save(flags); + bio_uninit(bio); bio->bi_next = cache->free_list_irq; cache->free_list_irq = bio; cache->nr_irq++; - local_irq_restore(flags); + } else { + goto out_free; } put_cpu(); + return; +out_free: + put_cpu(); + bio_free(bio); } /** |