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Violators will be prosecuted; Tue, 15 May 2018 09:03:51 -0400 Received: from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com [9.57.199.109]) by b01cxnp22033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w4FD3pQH45613056; Tue, 15 May 2018 13:03:51 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E8E3D112034; Tue, 15 May 2018 09:03:53 -0400 (EDT) Received: from pacoca.br.ibm.com (unknown [9.7.47.248]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP id 6E102112047; Tue, 15 May 2018 09:03:53 -0400 (EDT) From: Jose Ricardo Ziviani To: kernel-team@lists.ubuntu.com Subject: [Bionic][PATCH v3 13/21] blk-mq: avoid to write intermediate result to hctx->next_cpu Date: Tue, 15 May 2018 10:03:16 -0300 X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180515130324.23815-1-joserz@linux.vnet.ibm.com> References: <20180515130324.23815-1-joserz@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18051513-0040-0000-0000-0000042BA142 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009029; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000260; SDB=6.01032653; UDB=6.00527947; IPR=6.00811785; MB=3.00021126; MTD=3.00000008; XFM=3.00000015; UTC=2018-05-15 13:03:52 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18051513-0041-0000-0000-00000831B5AA Message-Id: <20180515130324.23815-14-joserz@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2018-05-15_03:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1805150132 X-Mailman-Approved-At: Wed, 16 May 2018 17:01:18 +0000 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Ming Lei BugLink: http://bugs.launchpad.net/bugs/1759723 This patch figures out the final selected CPU, then writes it to hctx->next_cpu once, then we can avoid to intermediate next cpu observed from other dispatch paths. Cc: Stefan Haberland Tested-by: Christian Borntraeger Reviewed-by: Christoph Hellwig Reviewed-by: Sagi Grimberg Signed-off-by: Ming Lei Signed-off-by: Jens Axboe (cherry picked from commit 476f8c98a9bccccbb97866974ffc80879adf2bbb) Signed-off-by: Jose Ricardo Ziviani --- block/blk-mq.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index ce5a08e3c0f3..15578008dcf2 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1258,26 +1258,24 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx) { bool tried = false; + int next_cpu = hctx->next_cpu; if (hctx->queue->nr_hw_queues == 1) return WORK_CPU_UNBOUND; if (--hctx->next_cpu_batch <= 0) { - int next_cpu; select_cpu: - next_cpu = cpumask_next_and(hctx->next_cpu, hctx->cpumask, + next_cpu = cpumask_next_and(next_cpu, hctx->cpumask, cpu_online_mask); if (next_cpu >= nr_cpu_ids) - next_cpu = cpumask_first_and(hctx->cpumask,cpu_online_mask); + next_cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask); /* * No online CPU is found, so have to make sure hctx->next_cpu * is set correctly for not breaking workqueue. */ if (next_cpu >= nr_cpu_ids) - hctx->next_cpu = cpumask_first(hctx->cpumask); - else - hctx->next_cpu = next_cpu; + next_cpu = cpumask_first(hctx->cpumask); hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH; } @@ -1285,7 +1283,7 @@ static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx) * Do unbound schedule if we can't find a online CPU for this hctx, * and it should only happen in the path of handling CPU DEAD. */ - if (!cpu_online(hctx->next_cpu)) { + if (!cpu_online(next_cpu)) { if (!tried) { tried = true; goto select_cpu; @@ -1295,10 +1293,13 @@ static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx) * Make sure to re-select CPU next time once after CPUs * in hctx->cpumask become online again. */ + hctx->next_cpu = next_cpu; hctx->next_cpu_batch = 1; return WORK_CPU_UNBOUND; } - return hctx->next_cpu; + + hctx->next_cpu = next_cpu; + return next_cpu; } static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,