From patchwork Sat Nov 10 15:13:15 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 10677245 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1AC8617D4 for ; Sat, 10 Nov 2018 15:13:31 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0AD10287D2 for ; Sat, 10 Nov 2018 15:13:31 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F33912900D; Sat, 10 Nov 2018 15:13:30 +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=-7.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham 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 A07D8287D2 for ; Sat, 10 Nov 2018 15:13:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726334AbeKKA6t (ORCPT ); Sat, 10 Nov 2018 19:58:49 -0500 Received: from mail-pl1-f194.google.com ([209.85.214.194]:39020 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726188AbeKKA6t (ORCPT ); Sat, 10 Nov 2018 19:58:49 -0500 Received: by mail-pl1-f194.google.com with SMTP id b5-v6so2262183pla.6 for ; Sat, 10 Nov 2018 07:13:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=VcNw0DpLmrkaGeRWqmaWgA1xrmMAHAatJCfbe/b7EMo=; b=DSMoqinT4P8NDdjLGhiT3oe8Mf8q+3WY3ZdRCXiWznRYCjNkjkLLxYccgDfsI5qTlw Zn0dyJrP3oMEgnaXkRUZ9HSRsC5owqyXD1Bj0FAKhTLhdjbCdzojn49mv77MS8AU4ogn M2YdmvF4qPT8P2Obg6aqcnVB3/dgYQ5AsIxFNI42EMub612T68cgrNuximpEIYyrrtUH hsZzzL0SH1mrLkLJ44evI5iCfh/nhviYtw7SIBp2YIn70a66qJJA3NpFt4iJpFyh0OZB pn16DKPo2auaflyWgeMCb1cCwLdW58H++iGccsVCyQ1c+lNmMB+eWA3ho1h50DyBEslM 4sxQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=VcNw0DpLmrkaGeRWqmaWgA1xrmMAHAatJCfbe/b7EMo=; b=Adm7eCbzOuIcj/MJvGzMxszeHUDCmMPi79uTA07d0W9B8nOrKkQ8jBvxouhE1jfYHD iUPeDsfV9E8ouaNZkBg4kifVxmKnXlIoP75C1v/Qk4VIQRVABJ2CEJxzTVCEFN933rgp UMuQSyzi57rVCJUPj2x8LODKVMRg0b/b7ClCcsXMgzU1+p96CPBYv0yJWEaU/8zO3uCH Yg/t0cgDD0wFjzGwRFLUbMVyJefKfWZcfIOmIMWiwfew/PtvZmBiNEjvf72t+VXmY4Y/ iPzoLioMsTbJJAfjz8Kwsp1tfemdXnx1XorhZUvgYEleOl2UTsVuuWjL6L59SWVT21Xl a+nQ== X-Gm-Message-State: AGRZ1gJDpzlAmWFRp+++MNLNUQWdSgwOhCQ82Bn+FT1iPlBhrv3dgIR+ b5EuBTaqBddSydI6XO8nsGDQieGenvk= X-Google-Smtp-Source: AJdET5evczOHBBSAIQ4cwx7vf/MZziXBSN0QEh9F52o31Jjrer5J1XwuDq3wum7Ak7ig9aZ7pL6kbQ== X-Received: by 2002:a17:902:2bc5:: with SMTP id l63-v6mr13184853plb.241.1541862808789; Sat, 10 Nov 2018 07:13:28 -0800 (PST) Received: from x1.localdomain (66.29.188.166.static.utbb.net. [66.29.188.166]) by smtp.gmail.com with ESMTPSA id d68-v6sm11178615pfa.80.2018.11.10.07.13.26 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 10 Nov 2018 07:13:27 -0800 (PST) From: Jens Axboe To: linux-block@vger.kernel.org Cc: Jens Axboe Subject: [PATCH 4/6] block: avoid ordered task state change for polled IO Date: Sat, 10 Nov 2018 08:13:15 -0700 Message-Id: <20181110151317.3813-5-axboe@kernel.dk> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181110151317.3813-1-axboe@kernel.dk> References: <20181110151317.3813-1-axboe@kernel.dk> 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 We only really need the barrier if we're going to be sleeping, if we're just polling we're fine with the __set_current_state() variant. Signed-off-by: Jens Axboe --- fs/block_dev.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index c039abfb2052..e7550b1f9670 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -237,12 +237,23 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, qc = submit_bio(&bio); for (;;) { - set_current_state(TASK_UNINTERRUPTIBLE); + /* + * Using non-atomic task state for polling + */ + __set_current_state(TASK_UNINTERRUPTIBLE); + if (!READ_ONCE(bio.bi_private)) break; + if (!(iocb->ki_flags & IOCB_HIPRI) || - !blk_poll(bdev_get_queue(bdev), qc)) + !blk_poll(bdev_get_queue(bdev), qc)) { + /* + * If we're scheduling, ensure that task state + * change is ordered and seen. + */ + smp_mb(); io_schedule(); + } } __set_current_state(TASK_RUNNING); @@ -403,13 +414,19 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) return -EIOCBQUEUED; for (;;) { - set_current_state(TASK_UNINTERRUPTIBLE); + /* + * See __blkdev_direct_IO_simple() loop + */ + __set_current_state(TASK_UNINTERRUPTIBLE); + if (!READ_ONCE(dio->waiter)) break; if (!(iocb->ki_flags & IOCB_HIPRI) || - !blk_poll(bdev_get_queue(bdev), qc)) + !blk_poll(bdev_get_queue(bdev), qc)) { + smp_mb(); io_schedule(); + } } __set_current_state(TASK_RUNNING);