Return-Path: Received: from mail-io1-f68.google.com ([209.85.166.68]:41530 "EHLO mail-io1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729629AbeLMR5I (ORCPT ); Thu, 13 Dec 2018 12:57:08 -0500 Received: by mail-io1-f68.google.com with SMTP id s22so2297546ioc.8 for ; Thu, 13 Dec 2018 09:57:08 -0800 (PST) From: Jens Axboe To: linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org Cc: hch@lst.de, jmoyer@redhat.com, clm@fb.com, Jens Axboe Subject: [PATCH 09/26] aio: only use blk plugs for > 2 depth submissions Date: Thu, 13 Dec 2018 10:56:28 -0700 Message-Id: <20181213175645.22181-10-axboe@kernel.dk> In-Reply-To: <20181213175645.22181-1-axboe@kernel.dk> References: <20181213175645.22181-1-axboe@kernel.dk> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Plugging is meant to optimize submission of a string of IOs, if we don't have more than 2 being submitted, don't bother setting up a plug. Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- fs/aio.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 522c04864d82..ed6c3914477a 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -69,6 +69,12 @@ struct aio_ring { struct io_event io_events[0]; }; /* 128 bytes + ring size */ +/* + * Plugging is meant to work with larger batches of IOs. If we don't + * have more than the below, then don't bother setting up a plug. + */ +#define AIO_PLUG_THRESHOLD 2 + #define AIO_RING_PAGES 8 struct kioctx_table { @@ -1919,7 +1925,8 @@ SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, if (nr > ctx->nr_events) nr = ctx->nr_events; - blk_start_plug(&plug); + if (nr > AIO_PLUG_THRESHOLD) + blk_start_plug(&plug); for (i = 0; i < nr; i++) { struct iocb __user *user_iocb; @@ -1932,7 +1939,8 @@ SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, if (ret) break; } - blk_finish_plug(&plug); + if (nr > AIO_PLUG_THRESHOLD) + blk_finish_plug(&plug); percpu_ref_put(&ctx->users); return i ? i : ret; @@ -1959,7 +1967,8 @@ COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id, if (nr > ctx->nr_events) nr = ctx->nr_events; - blk_start_plug(&plug); + if (nr > AIO_PLUG_THRESHOLD) + blk_start_plug(&plug); for (i = 0; i < nr; i++) { compat_uptr_t user_iocb; @@ -1972,7 +1981,8 @@ COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id, if (ret) break; } - blk_finish_plug(&plug); + if (nr > AIO_PLUG_THRESHOLD) + blk_finish_plug(&plug); percpu_ref_put(&ctx->users); return i ? i : ret; -- 2.17.1