From: Jens Axboe <axboe@kernel.dk>
To: Jan Kara <jack@suse.cz>
Cc: linux-block@vger.kernel.org, Paolo Valente <paolo.valente@linaro.org>
Subject: Re: [PATCH 1/8] block: Provide icq in request allocation data
Date: Tue, 23 Nov 2021 16:10:21 -0700 [thread overview]
Message-ID: <f4bb858a-bb9e-fec3-4ac6-16960879783e@kernel.dk> (raw)
In-Reply-To: <20211123223045.GC8583@quack2.suse.cz>
On 11/23/21 3:30 PM, Jan Kara wrote:
> On Tue 23-11-21 09:06:47, Jens Axboe wrote:
>> On 11/23/21 3:29 AM, Jan Kara wrote:
>>> Currently we lookup ICQ only after the request is allocated. However BFQ
>>> will want to decide how many scheduler tags it allows a given bfq queue
>>> (effectively a process) to consume based on cgroup weight. So lookup ICQ
>>> earlier and provide it in struct blk_mq_alloc_data so that BFQ can use
>>> it.
>>
>> I've been trying to clean this path up a bit, since I don't like having
>> something that just one scheduler needs in the fast path. See:
>>
>> https://git.kernel.dk/cgit/linux-block/commit/?h=perf-wip&id=f1f8191a8f9a0cdcd5ad99dfd7e551e8f444bec5
>>
>> Would be better if we could avoid adding io_cq to blk_mq_alloc_data for
>> that reason, would it be possible to hide this away in the sched code
>> instead on top of the above?
>
> Understood. We could certainly handle ICQ allocation & assignment only
> inside BFQ. Just this would mean we would need to lookup ICQ once in
> bfq_limit_depth() and then second time in bfq_prepare_request(). I
> guess not a huge deal given the amount of work BFQ does for each
> request anyway.
Exactly, it's noise there, but would not be in the general core.
> So can I pull the above commit into the series and
> rebase this patch on top of it?
It's in my for-5.17/block, but might get rebased... For a series of
patches like this, basing on it would be fine though, and you should
just do that.
--
Jens Axboe
next prev parent reply other threads:[~2021-11-23 23:10 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-23 10:29 [PATCH 0/8 v4] bfq: Limit number of allocated scheduler tags per cgroup Jan Kara
2021-11-23 10:29 ` [PATCH 1/8] block: Provide icq in request allocation data Jan Kara
2021-11-23 16:06 ` Jens Axboe
2021-11-23 22:30 ` Jan Kara
2021-11-23 23:10 ` Jens Axboe [this message]
2021-11-23 10:29 ` [PATCH 2/8] bfq: Track number of allocated requests in bfq_entity Jan Kara
2021-11-23 10:29 ` [PATCH 3/8] bfq: Store full bitmap depth in bfq_data Jan Kara
2021-11-23 10:29 ` [PATCH 4/8] bfq: Limit number of requests consumed by each cgroup Jan Kara
2021-11-23 10:29 ` [PATCH 5/8] bfq: Limit waker detection in time Jan Kara
2021-11-23 10:29 ` [PATCH 6/8] bfq: Provide helper to generate bfqq name Jan Kara
2021-11-23 10:29 ` [PATCH 7/8] bfq: Log waker detections Jan Kara
2021-11-23 10:29 ` [PATCH 8/8] bfq: Do not let waker requests skip proper accounting Jan Kara
-- strict thread matches above, loose matches on Subject: below --
2021-10-06 17:31 [PATCH 0/8 v3] bfq: Limit number of allocated scheduler tags per cgroup Jan Kara
2021-10-06 17:31 ` [PATCH 1/8] block: Provide icq in request allocation data Jan Kara
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