Commit 954d3e95 authored May 01, 2005 by Ken Chen Committed by Linus Torvalds May 01, 2005

[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: 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>

parent 644d3a08

fs/aio.c

+8 −4

Original line number	Diff line number	Diff line
		@@ -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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