From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752364AbeBHOhC (ORCPT ); Thu, 8 Feb 2018 09:37:02 -0500 Received: from mailout4.samsung.com ([203.254.224.34]:54294 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750961AbeBHOg7 (ORCPT ); Thu, 8 Feb 2018 09:36:59 -0500 DKIM-Filter: OpenDKIM Filter v2.11.0 mailout4.samsung.com 20180208143657epoutp04425092afd888005cafece3d23525af67~RYHf0D2452521625216epoutp04A X-AuditID: b6c32a39-467ff70000000fc5-35-5a7c6088ad84 From: Nitesh Shetty To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk Cc: linux-block@vger.kernel.org, axboe@fb.com, linux-nvme@lists.infradead.org, nj.shetty@samsung.com, joshi.k@samsung.com Subject: [PATCH] blk: optimization for classic polling Date: Sun, 30 May 2083 09:51:06 +0530 Message-id: <3578876466-3733-1-git-send-email-nj.shetty@samsung.com> X-Mailer: git-send-email 2.7.4 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrGIsWRmVeSWpSXmKPExsWy7bCmgW5HQk2UwbYllhb/9xxjszj6/y2b xd5b2hZ79p5ksbi8aw6bxfxlT9kttv2ez2xx/u9xVgcOj4nN79g9Ni+p9+jbsorR4/MmOY9N T94yBbBGcdmkpOZklqUW6dslcGW8nd7JWHBYomLRhn7WBsbPwl2MnBwSAiYSdyY0MYPYQgI7 GCU2v+brYuQCsr8zStx9uosRpujTuXYWiMQGRonGYwsZIZx2Jonf9zrZuxg5ONgEtCVO/+cA aRARiJLY1naHESTMLFAtsfCCKkhYWMBMYt+sLrBqFgFViY4rSSBhXgEXidkvnzJBrJKTuHmu kxlkuoTAV1aJZ+e+sUMkXCQenfoKdY+wxKvjW8DmSAhIS1w6agtR380ocaN1NVTNFEaJGXP1 IWx7iYt7/oItYBbgk3j3tYcVopdXoqNNCKLEQ2LRiQ5WCNtRYuH+Z0yQMImVeHZqLusERskF jAyrGMVSC4pz01OLDQtM9YoTc4tL89L1kvNzNzGCY0/LcgfjsXM+hxgFOBiVeHhfxNVECbEm lhVX5h5ilOBgVhLh3SMKFOJNSaysSi3Kjy8qzUktPsQozcGiJM4bEOASJSSQnliSmp2aWpBa BJNl4uCUamBcvu2pzmnjFOvzUvuE5vuebDt9aI9qUbbKzNMGXzcufnNSZ5Ln2aVpYSzijLdK 736O26gcIiKxU0ny3KSJ13ST1Y/6bXh0X/2y8upJpvNrFhQsrmkJEb1iU9zkHC+Zs/qd9+Qn T66xB+f/rg8OWjc3b7t9SefrpyfOFoeeqZPz31n4tGX/E8f7SizFGYmGWsxFxYkAlHHv47kC AAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrCJMWRmVeSWpSXmKPExsVy+t9jQd32hJoog9PrdS3+7znGZnH0/1s2 i723tC327D3JYnF51xw2i/nLnrJbbPs9n9ni/N/jrA4cHhOb37F7bF5S79G3ZRWjx+dNch6b nrxlCmCN4rJJSc3JLEst0rdL4Mp4O72TseCwRMWiDf2sDYyfhbsYOTkkBEwkPp1rZ+li5OIQ EljHKLHw2gY2CKeTSWJZ+1kgh4ODTUBb4vR/DpAGEYEoiYWfmllBwswC1RJn59SAhIUFzCT2 zepiBwmzCKhKdFxJAgnzCrhIzH75lAlilZzEzXOdzBMYuRYwMqxilEwtKM5Nzy02KjDMSy3X K07MLS7NS9dLzs/dxAgMi22Htfp2MN5fEn+IUYCDUYmHd0JMTZQQa2JZcWXuIUYJDmYlEd49 okAh3pTEyqrUovz4otKc1OJDjNIcLErivLfzjkUKCaQnlqRmp6YWpBbBZJk4OKUaGLeLiMfd 07zcU77s9PtXX/8XuuguKAzfJ/zvzwGxrvxl11PPpG7191oyY4lxx47mm12V5abnE7oP6a1X TbwU7bMgp+LO2c5Vau80p5iJ9zhvMsu5yrU6d2fctNqzkwOvGX3SOTG5ReSFYM6740oqd7Z0 veheO/N4ksShufkut/5f+//hzOoz2ZOUWIozEg21mIuKEwGv71ViBwIAAA== X-CMS-MailID: 20180208143655epcas1p444bf34705526b7839a5a135f82761aad X-Msg-Generator: CA CMS-TYPE: 101P X-CMS-RootMailID: 20180208143655epcas1p444bf34705526b7839a5a135f82761aad X-RootMTR: 20180208143655epcas1p444bf34705526b7839a5a135f82761aad References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 4a181fc..a87d8b7 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -236,9 +236,13 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, 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)) + if (!(iocb->ki_flags & IOCB_HIPRI)) io_schedule(); + else if (!blk_poll(bdev_get_queue(bdev), qc)) { + if (need_resched()) + set_current_state(TASK_RUNNING); + io_schedule(); + } } __set_current_state(TASK_RUNNING); @@ -401,9 +405,13 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) if (!READ_ONCE(dio->waiter)) break; - if (!(iocb->ki_flags & IOCB_HIPRI) || - !blk_poll(bdev_get_queue(bdev), qc)) + if (!(iocb->ki_flags & IOCB_HIPRI)) io_schedule(); + else if (!blk_poll(bdev_get_queue(bdev), qc)) { + if (need_resched()) + set_current_state(TASK_RUNNING); + io_schedule(); + } } __set_current_state(TASK_RUNNING); diff --git a/fs/direct-io.c b/fs/direct-io.c index a0ca9e4..c815ac9 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -518,9 +518,13 @@ static struct bio *dio_await_one(struct dio *dio) __set_current_state(TASK_UNINTERRUPTIBLE); dio->waiter = current; spin_unlock_irqrestore(&dio->bio_lock, flags); - if (!(dio->iocb->ki_flags & IOCB_HIPRI) || - !blk_poll(dio->bio_disk->queue, dio->bio_cookie)) + if (!(dio->iocb->ki_flags & IOCB_HIPRI)) io_schedule(); + else if (!blk_poll(dio->bio_disk->queue, dio->bio_cookie)) { + if (need_resched()) + __set_current_state(TASK_RUNNING); + io_schedule(); + } /* wake up sets us TASK_RUNNING */ spin_lock_irqsave(&dio->bio_lock, flags); dio->waiter = NULL; diff --git a/fs/iomap.c b/fs/iomap.c index afd1635..b51569d 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -1072,10 +1072,14 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, break; if (!(iocb->ki_flags & IOCB_HIPRI) || - !dio->submit.last_queue || - !blk_poll(dio->submit.last_queue, - dio->submit.cookie)) + !dio->submit.last_queue) io_schedule(); + else if (!blk_poll(dio->submit.last_queue, + dio->submit.cookie)) { + if (need_resched()) + set_current_state(TASK_RUNNING); + io_schedule(); + } } __set_current_state(TASK_RUNNING); } -- 2.7.4