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Code Issues Releases Wiki Activity

io_uring: don't bounce submit_state cachelines

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struct io_submit_state contains struct io_comp_state and so
locked_free_*, that renders cachelines around ->locked_free* being
invalidated on most non-inline completions, that may terrorise caches if
submissions and completions are done by different tasks.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/290cb5412b76892e8631978ee8ab9db0c6290dd5.1621201931.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-05-16 22:58:12 +01:00 committed by Jens Axboe
parent d068b5068d
commit d0acdee296
1 changed files with 9 additions and 11 deletions
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20
fs/io_uring.c
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@ -298,11 +298,8 @@ struct io_sq_data {
struct io_comp_state {
struct io_kiocb *reqs[IO_COMPL_BATCH];
unsigned int nr;
unsigned int locked_free_nr;
/* inline/task_work completion list, under ->uring_lock */
struct list_head free_list;
/* IRQ completion list, under ->completion_lock */
struct list_head locked_free_list;
};
struct io_submit_link {
@ -379,6 +376,9 @@ struct io_ring_ctx {
} ____cacheline_aligned_in_smp;
struct io_submit_state submit_state;
/* IRQ completion list, under ->completion_lock */
struct list_head locked_free_list;
unsigned int locked_free_nr;
struct io_rings *rings;
@ -1189,7 +1189,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
init_llist_head(&ctx->rsrc_put_llist);
INIT_LIST_HEAD(&ctx->tctx_list);
INIT_LIST_HEAD(&ctx->submit_state.comp.free_list);
INIT_LIST_HEAD(&ctx->submit_state.comp.locked_free_list);
INIT_LIST_HEAD(&ctx->locked_free_list);
return ctx;
err:
kfree(ctx->dummy_ubuf);
@ -1592,8 +1592,6 @@ static void io_req_complete_post(struct io_kiocb *req, long res,
* free_list cache.
*/
if (req_ref_put_and_test(req)) {
struct io_comp_state *cs = &ctx->submit_state.comp;
if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK)) {
if (req->flags & (REQ_F_LINK_TIMEOUT | REQ_F_FAIL))
io_disarm_next(req);
@ -1604,8 +1602,8 @@ static void io_req_complete_post(struct io_kiocb *req, long res,
}
io_dismantle_req(req);
io_put_task(req->task, 1);
list_add(&req->compl.list, &cs->locked_free_list);
cs->locked_free_nr++;
list_add(&req->compl.list, &ctx->locked_free_list);
ctx->locked_free_nr++;
} else {
if (!percpu_ref_tryget(&ctx->refs))
req = NULL;
@ -1660,8 +1658,8 @@ static void io_flush_cached_locked_reqs(struct io_ring_ctx *ctx,
struct io_comp_state *cs)
{
spin_lock_irq(&ctx->completion_lock);
list_splice_init(&cs->locked_free_list, &cs->free_list);
cs->locked_free_nr = 0;
list_splice_init(&ctx->locked_free_list, &cs->free_list);
ctx->locked_free_nr = 0;
spin_unlock_irq(&ctx->completion_lock);
}
@ -1677,7 +1675,7 @@ static bool io_flush_cached_reqs(struct io_ring_ctx *ctx)
* locked cache, grab the lock and move them over to our submission
* side cache.
*/
if (READ_ONCE(cs->locked_free_nr) > IO_COMPL_BATCH)
if (READ_ONCE(ctx->locked_free_nr) > IO_COMPL_BATCH)
io_flush_cached_locked_reqs(ctx, cs);
nr = state->free_reqs;