From: Jens Axboe <axboe@kernel.dk>
To: Christoph Hellwig <hch@infradead.org>
Cc: Andrzej Jakowski <andrzej.jakowski@linux.intel.com>,
song@kernel.org, linux-block@vger.kernel.org,
linux-raid@vger.kernel.org,
Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Subject: Re: [PATCH 1/2] block: introduce polling on bio level
Date: Fri, 31 Jan 2020 21:41:58 -0700 [thread overview]
Message-ID: <ffb832a5-e946-2575-d820-8c8831e2ed99@kernel.dk> (raw)
In-Reply-To: <20200131063527.GC6267@infradead.org>
On 1/30/20 11:35 PM, Christoph Hellwig wrote:
> On Wed, Jan 29, 2020 at 09:01:49PM -0700, Jens Axboe wrote:
>> blk_poll() used to be a pointer in the queue, but since we just had
>> one implementation, we got rid of it. Might make sense to
>> reintroduce that, and just make it an optimized indirect call. I
>> think that would be prettier than add the bio hack in the middle of
>> it, and you're having to add a queue pointer anyway.
>
> Well, the other reason is to avoid an indirect call for the blk-mq
> case, which are fairly expensive. In fact I'm pretty sure we avoid
> indirect calls from the bio layer into blk-mq entirely for the fast
> path at the moment, and it would be great to keep it that way.
Sure, my suggestion was to provide it as an alternative - if set,
then call that. Though with the optimized indirect calls, at least
it's just a branch, actual call is the same.
This patch sets a bit in no mans land right now. It's duplicating
the main loop, and it's shoved in the middle of the function. This
has to get cleaned up.
--
Jens Axboe
next prev parent reply other threads:[~2020-02-01 4:41 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-26 4:41 [PATCH 0/2] Enable polling on stackable devices Andrzej Jakowski
2020-01-26 4:41 ` [PATCH 1/2] block: introduce polling on bio level Andrzej Jakowski
2020-01-30 4:01 ` Jens Axboe
2020-01-31 6:35 ` Christoph Hellwig
2020-02-01 4:41 ` Jens Axboe [this message]
2020-01-31 6:34 ` Christoph Hellwig
2020-01-31 18:51 ` Andrzej Jakowski
2020-02-01 8:20 ` Christoph Hellwig
2020-01-26 4:41 ` [PATCH 2/2] md: enable io polling Andrzej Jakowski
2020-01-31 6:36 ` Christoph Hellwig
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