From: Jens Axboe <axboe@fb.com>
To: Shaohua Li <shli@fb.com>, Christoph Hellwig <hch@infradead.org>
Cc: <linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<Kernel-team@fb.com>
Subject: Re: [PATCH 1/3] blk-mq: add an API to estimate hardware queue node
Date: Tue, 29 Mar 2016 10:50:11 -0600 [thread overview]
Message-ID: <56FAB243.5020804@fb.com> (raw)
In-Reply-To: <20160329164722.GA1208161@devbig084.prn1.facebook.com>
On 03/29/2016 10:47 AM, Shaohua Li wrote:
> On Tue, Mar 29, 2016 at 12:24:43AM -0700, Christoph Hellwig wrote:
>> On Fri, Mar 25, 2016 at 02:36:30PM -0700, Shaohua Li wrote:
>>> we allocate most data structure in device's node, but some data
>>> structures are not for DMA and mostly used by specific cpus/node which
>>> could diff from device's node. Allocating such hot data in device's
>>> node doesn't make sense. Add an API to estimate hardware queue node.
>>> This can be used before blk-mq actually establishes the mapping. This
>>> API runs slow, but it only used in initialization time.
>>
>> I think this is the wrong way around. I've got some proprotype code
>> that just leaves the cpu assignments to the drivers and picks it up
>> in blk-mq. Give me a few days to post it..
>
> This looks weird, shouldn't the cpu assignment be determined by block
> core (blk-mq) because block core decides how to use the queue?
I agree, that belongs in the blk-mq proper, the driver should just
follow the rules outlined, not impose their own in this regard. It'll
also help with irq affinity mappings, once we get that in.
--
Jens Axboe
next prev parent reply other threads:[~2016-03-29 16:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-25 21:36 [PATCH 1/3] blk-mq: add an API to estimate hardware queue node Shaohua Li
2016-03-25 21:36 ` [PATCH 2/3] blk-mq: allocate blk_mq_tags and requests in correct node Shaohua Li
2016-03-25 21:36 ` [PATCH 3/3] nvme: allocate nvme_queue " Shaohua Li
2016-03-29 7:24 ` [PATCH 1/3] blk-mq: add an API to estimate hardware queue node Christoph Hellwig
2016-03-29 16:47 ` Shaohua Li
2016-03-29 16:50 ` Jens Axboe [this message]
2016-03-29 17:44 ` Christoph Hellwig
2016-03-29 20:51 ` Jens Axboe
2016-03-29 21:20 ` Christoph Hellwig
2016-03-29 21:22 ` Jens Axboe
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