From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>,
[email protected], [email protected]
Subject: [PATCH 2/2] io_uring: batch getting pcpu references
Date: Wed, 18 Dec 2019 01:28:39 +0300 [thread overview]
Message-ID: <b72c5ec7f6d9a9881948de6cb88d30cc5e0354e9.1576621553.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>
percpu_ref_tryget() has its own overhead. Instead getting a reference
for each request, grab a bunch once per io_submit_sqes().
basic benchmark with submit and wait 128 non-linked nops showed ~5%
performance gain. (7044 KIOPS vs 7423)
Signed-off-by: Pavel Begunkov <[email protected]>
---
For notice: it could be done without @extra_refs variable,
but looked too tangled because of gotos.
fs/io_uring.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index cf4138f0e504..6c85dfc62224 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -845,9 +845,6 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
struct io_kiocb *req;
- if (!percpu_ref_tryget(&ctx->refs))
- return NULL;
-
if (!state) {
req = kmem_cache_alloc(req_cachep, gfp);
if (unlikely(!req))
@@ -3929,6 +3926,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
struct io_submit_state state, *statep = NULL;
struct io_kiocb *link = NULL;
int i, submitted = 0;
+ unsigned int extra_refs;
bool mm_fault = false;
/* if we have a backlog and couldn't flush it all, return BUSY */
@@ -3941,6 +3939,10 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
statep = &state;
}
+ if (!percpu_ref_tryget_many(&ctx->refs, nr))
+ return -EAGAIN;
+ extra_refs = nr;
+
for (i = 0; i < nr; i++) {
struct io_kiocb *req = io_get_req(ctx, statep);
@@ -3949,6 +3951,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
submitted = -EAGAIN;
break;
}
+ --extra_refs;
if (!io_get_sqring(ctx, req)) {
__io_free_req(req);
break;
@@ -3976,6 +3979,8 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
io_queue_link_head(link);
if (statep)
io_submit_state_end(&state);
+ if (extra_refs)
+ percpu_ref_put_many(&ctx->refs, extra_refs);
/* Commit SQ ring head once we've consumed and submitted all SQEs */
io_commit_sqring(ctx);
--
2.24.0
next prev parent reply other threads:[~2019-12-17 22:29 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-17 22:28 [PATCH 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-17 22:28 ` [PATCH 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-17 23:42 ` Jens Axboe
2019-12-18 16:26 ` Tejun Heo
2019-12-18 17:49 ` Dennis Zhou
2019-12-21 15:36 ` Pavel Begunkov
2019-12-17 22:28 ` Pavel Begunkov [this message]
2019-12-17 23:21 ` [PATCH 2/2] io_uring: batch getting pcpu references Jens Axboe
2019-12-17 23:31 ` Jens Axboe
2019-12-18 9:25 ` Pavel Begunkov
2019-12-18 9:23 ` Pavel Begunkov
2019-12-18 0:02 ` Jens Axboe
2019-12-18 10:41 ` Pavel Begunkov
2019-12-21 16:15 ` [PATCH v2 0/3] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-21 16:15 ` [PATCH v2 1/3] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-21 16:15 ` [PATCH v2 2/3] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-21 16:15 ` [PATCH RFC v2 3/3] io_uring: batch get(ctx->ref) across submits Pavel Begunkov
2019-12-21 16:20 ` Pavel Begunkov
2019-12-21 16:38 ` Jens Axboe
2019-12-21 16:48 ` Pavel Begunkov
2019-12-21 17:01 ` Jens Axboe
2019-12-21 17:26 ` Pavel Begunkov
2019-12-21 20:12 ` [PATCH v3 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-21 20:12 ` [PATCH v3 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-21 20:12 ` [PATCH v3 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-21 21:56 ` Pavel Begunkov
2019-12-28 11:13 ` [PATCH v4 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-28 11:13 ` [PATCH v4 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-28 11:13 ` [PATCH v4 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-28 11:15 ` Pavel Begunkov
2019-12-28 17:03 ` Jens Axboe
2019-12-28 18:37 ` Pavel Begunkov
2019-12-30 3:33 ` Brian Gianforcaro
2019-12-30 18:45 ` Pavel Begunkov
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