From 954d3e95369cf73b4bc1e570729f68264a0e6fe0 Mon Sep 17 00:00:00 2001 From: Ken Chen Date: Sun, 1 May 2005 08:59:16 -0700 Subject: [PATCH] [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 Cc: Benjamin LaHaise Cc: Suparna Bhattacharya Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/aio.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 674bb47fed2..7afa222f680 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -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); - list_add_tail(&req->ki_run_list, &ctx->run_list); - /* drain the run list */ - while (__aio_run_iocbs(ctx)) - ; + 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; -- 2.20.1