From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752214AbeBHPXc (ORCPT ); Thu, 8 Feb 2018 10:23:32 -0500 Received: from mga18.intel.com ([134.134.136.126]:65426 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751786AbeBHPXb (ORCPT ); Thu, 8 Feb 2018 10:23:31 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,479,1511856000"; d="scan'208";a="18306797" Date: Thu, 8 Feb 2018 08:27:30 -0700 From: Keith Busch To: Nitesh Shetty Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, linux-block@vger.kernel.org, axboe@fb.com, linux-nvme@lists.infradead.org, joshi.k@samsung.com Subject: Re: [PATCH] blk: optimization for classic polling Message-ID: <20180208152730.GA4906@localhost.localdomain> References: <3578876466-3733-1-git-send-email-nj.shetty@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3578876466-3733-1-git-send-email-nj.shetty@samsung.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, May 30, 2083 at 09:51:06AM +0530, Nitesh Shetty wrote: > This removes the dependency on interrupts to wake up task. Set task > state as TASK_RUNNING, if need_resched() returns true, > while polling for IO completion. > Earlier, polling task used to sleep, relying on interrupt to wake it up. > This made some IO take very long when interrupt-coalescing is enabled in > NVMe. > > Reference: > http://lists.infradead.org/pipermail/linux-nvme/2018-February/015435.html > Signed-off-by: Nitesh Shetty > --- > fs/block_dev.c | 16 ++++++++++++---- > fs/direct-io.c | 8 ++++++-- > fs/iomap.c | 10 +++++++--- > 3 files changed, 25 insertions(+), 9 deletions(-) I think it'd be simpler to have blk_poll set it back to running if need_resched is true rather than repeat this patter across all the callers: --- diff --git a/block/blk-mq.c b/block/blk-mq.c index df93102e2149..40285fe1c8ad 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3164,6 +3164,7 @@ static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq) cpu_relax(); } + set_current_state(TASK_RUNNING); return false; } --