From: luferry <luferry@163.com>
To: "Christoph Hellwig" <hch@lst.de>
Cc: "Jens Axboe" <axboe@kernel.dk>,
"Dongli Zhang" <dongli.zhang@oracle.com>,
"Ming Lei" <ming.lei@redhat.com>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re:Re: [PATCH] make blk_mq_map_queues more friendly for cpu topology
Date: Wed, 27 Mar 2019 17:17:18 +0800 (CST) [thread overview]
Message-ID: <764f3c.12445.169be70834b.Coremail.luferry@163.com> (raw)
In-Reply-To: <20190327081619.GG20525@lst.de>
Actually, I just bought one vm from public cloud provider and run into this problem.
after reading code and compare pci device info, I reproduce this scenario.
Since common users cannot change msi vector numbers, so I suggest blk_mq_map_queues to be
more friendly. blk_mq_map_queues may be the last choice.
At 2019-03-27 16:16:19, "Christoph Hellwig" <hch@lst.de> wrote:
>On Tue, Mar 26, 2019 at 03:55:10PM +0800, luferry wrote:
>>
>>
>>
>> At 2019-03-26 15:39:54, "Christoph Hellwig" <hch@lst.de> wrote:
>> >Why isn't this using the automatic PCI-level affinity assignment to
>> >start with?
>>
>> When enable virtio-blk with multi queues but with only 2 msix-vector.
>> vp_dev->per_vq_vectors will be false, vp_get_vq_affintity will return NULL directly
>> so blk_mq_virtio_map_queues will fallback to blk_mq_map_queues.
>
>What is the point of the multiqueue mode if you don't have enough
>(virtual) MSI-X vectors?
next prev parent reply other threads:[~2019-03-27 9:32 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-25 15:26 [PATCH] make blk_mq_map_queues more friendly for cpu topology luferry
2019-03-26 7:39 ` Christoph Hellwig
2019-03-26 7:55 ` luferry
2019-03-27 8:16 ` Christoph Hellwig
2019-03-27 9:17 ` luferry [this message]
2019-03-27 9:39 ` Dongli Zhang
2019-03-27 9:53 ` luferry
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