From patchwork Thu Feb 8 15:27:30 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Keith Busch X-Patchwork-Id: 10207281 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 2A2BA602D8 for ; Thu, 8 Feb 2018 15:24:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1BEC129563 for ; Thu, 8 Feb 2018 15:24:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1056129560; Thu, 8 Feb 2018 15:24:01 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 744C329560 for ; Thu, 8 Feb 2018 15:23:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752100AbeBHPXb (ORCPT ); Thu, 8 Feb 2018 10:23:31 -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 Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 Feb 2018 07:23:29 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,479,1511856000"; d="scan'208";a="18306797" Received: from unknown (HELO localhost.localdomain) ([10.232.112.44]) by fmsmga002.fm.intel.com with ESMTP; 08 Feb 2018 07:23:29 -0800 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-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-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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; }