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[PATCH] aio: optimize io_submit_one()

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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: Ken Chen <kenneth.w.chen@intel.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Suparna Bhattacharya <suparna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ken Chen 2005-05-01 08:59:16 -07:00 committed by Linus Torvalds
parent 644d3a088a
commit 954d3e9536
1 changed files with 8 additions and 4 deletions
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12
fs/aio.c
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@ -1514,10 +1514,14 @@ int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
goto out_put_req; goto out_put_req;
spin_lock_irq(&ctx->ctx_lock); spin_lock_irq(&ctx->ctx_lock);
list_add_tail(&req->ki_run_list, &ctx->run_list); if (likely(list_empty(&ctx->run_list))) {
/* drain the run list */ aio_run_iocb(req);
while (__aio_run_iocbs(ctx)) } 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); spin_unlock_irq(&ctx->ctx_lock);
aio_put_req(req); /* drop extra ref to req */ aio_put_req(req); /* drop extra ref to req */
return 0; return 0;