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From: Jianchao Wang <jianchao.w.wang@oracle.com>
To: axboe@kernel.dk
Cc: ming.lei@redhat.com, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH V6 3/5] blk-mq: ensure hctx to be ran on mapped cpu when issue directly
Date: Tue, 13 Nov 2018 17:56:54 +0800	[thread overview]
Message-ID: <1542103016-21037-4-git-send-email-jianchao.w.wang@oracle.com> (raw)
In-Reply-To: <1542103016-21037-1-git-send-email-jianchao.w.wang@oracle.com>

When issue request directly and the task is migrated out of the
original cpu where it allocates request, hctx could be ran on
the cpu where it is not mapped.
To fix this,
 - insert the request forcibly if BLK_MQ_F_BLOCKING is set.
 - check whether the current is mapped to the hctx, if not, insert
   forcibly.
 - invoke __blk_mq_issue_directly under preemption disabled.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
---
 block/blk-mq.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 11c52bb..58f15cc 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1776,6 +1776,17 @@ static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
 	blk_status_t ret = BLK_STS_RESOURCE;
 	int srcu_idx;
 
+	if (hctx->flags & BLK_MQ_F_BLOCKING) {
+		force = true;
+		goto out;
+	}
+
+	if (unlikely(!cpumask_test_cpu(get_cpu(), hctx->cpumask))) {
+		put_cpu();
+		force = true;
+		goto out;
+	}
+
 	hctx_lock(hctx, &srcu_idx);
 	/*
 	 * hctx_lock is needed before checking quiesced flag.
@@ -1808,7 +1819,8 @@ static blk_status_t blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
 
 out_unlock:
 	hctx_unlock(hctx, srcu_idx);
-
+	put_cpu();
+out:
 	switch (ret) {
 	case BLK_STS_OK:
 		break;
-- 
2.7.4


  parent reply	other threads:[~2018-11-13  9:57 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-13  9:56 [PATCH V6 0/5] blk-mq: refactor and fix on issue request directly Jianchao Wang
2018-11-13  9:56 ` [PATCH V6 1/5] blk-mq: refactor the code of " Jianchao Wang
2018-11-13  9:56 ` [PATCH V6 2/5] blk-mq: fix issue directly case when q is stopped or quiesced Jianchao Wang
2018-11-13  9:56 ` Jianchao Wang [this message]
2018-11-13 13:44   ` [PATCH V6 3/5] blk-mq: ensure hctx to be ran on mapped cpu when issue directly Jens Axboe
2018-11-14  2:15     ` jianchao.wang
2018-11-14  3:02       ` Ming Lei
2018-11-14  3:38         ` jianchao.wang
2018-11-13  9:56 ` [PATCH V6 4/5] blk-mq: issue directly with bypass 'false' in blk_mq_sched_insert_requests Jianchao Wang
2018-11-13  9:56 ` [PATCH V6 5/5] blk-mq: replace and kill blk_mq_request_issue_directly Jianchao Wang

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