Commit 954d3e95 authored by Ken Chen's avatar Ken Chen Committed by Linus Torvalds

[PATCH] aio: optimize io_submit_one()

This patch optimizes io_submit_one to call aio_run_iocb() directly if
ctx->run_list is empty.  When the list is empty, the operation of adding to
the list, then call to __aio_run_iocbs() is unnecessary because these
operations are done in one atomic step.  ctx->run_list always has only one
element in this case.  This optimization speeds up industry standard db
transaction processing benchmark by 0.2%.
Signed-off-by: default avatarKen Chen <kenneth.w.chen@intel.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Suparna Bhattacharya <suparna@in.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 644d3a08
......@@ -1514,10 +1514,14 @@ int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
goto out_put_req;
spin_lock_irq(&ctx->ctx_lock);
if (likely(list_empty(&ctx->run_list))) {
aio_run_iocb(req);
} else {
list_add_tail(&req->ki_run_list, &ctx->run_list);
/* drain the run list */
while (__aio_run_iocbs(ctx))
;
}
spin_unlock_irq(&ctx->ctx_lock);
aio_put_req(req); /* drop extra ref to req */
return 0;
......
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