From: Christoph Hellwig <hch@infradead.org>
To: Jens Axboe <axboe@fb.com>
Cc: axboe@kernel.dk, linux-block@vger.kernel.org, paolo.valente@linaro.org
Subject: Re: [PATCH 1/7] block: use legacy path for flush requests for MQ with a scheduler
Date: Mon, 5 Dec 2016 05:05:17 -0800 [thread overview]
Message-ID: <20161205130517.GA7100@infradead.org> (raw)
In-Reply-To: <1480734921-23701-2-git-send-email-axboe@fb.com>
On Fri, Dec 02, 2016 at 08:15:15PM -0700, Jens Axboe wrote:
> No functional changes with this patch, it's just in preparation for
> supporting legacy schedulers on blk-mq.
Ewww. I think without refactoring to clear what 'use_mq_path'
means here and better naming this is a total non-started. Even with
that we'll now have yet another code path to worry about. Is there
any chance to instead consolidate into a single path?
> struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
> {
> - if (q->mq_ops)
> + if (blk_use_mq_path(q))
> return blk_mq_alloc_request(q, rw,
> (gfp_mask & __GFP_DIRECT_RECLAIM) ?
> 0 : BLK_MQ_REQ_NOWAIT);
So now with blk-mq and an elevator set we go into blk_old_get_request,
hich will simply allocate new requests. How does this not break
every existing driver?
next prev parent reply other threads:[~2016-12-05 13:05 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-03 3:15 [PATCHSET/RFC] Make legacy IO schedulers work with blk-mq Jens Axboe
2016-12-03 3:15 ` [PATCH 1/7] block: use legacy path for flush requests for MQ with a scheduler Jens Axboe
2016-12-05 13:05 ` Christoph Hellwig [this message]
2016-12-05 15:07 ` Jens Axboe
2016-12-05 15:49 ` Johannes Thumshirn
2016-12-05 15:49 ` Jens Axboe
2016-12-05 22:40 ` Mike Snitzer
2016-12-05 22:50 ` Jens Axboe
2016-12-06 19:50 ` Mike Snitzer
2016-12-05 17:00 ` Ming Lei
2016-12-05 17:09 ` Jens Axboe
2016-12-05 19:22 ` Ming Lei
2016-12-05 19:35 ` Jens Axboe
2016-12-03 3:15 ` [PATCH 2/7] cfq-iosched: use appropriate run queue function Jens Axboe
2016-12-05 8:48 ` Johannes Thumshirn
2016-12-05 15:12 ` Jens Axboe
2016-12-05 15:18 ` Johannes Thumshirn
2016-12-05 13:06 ` Christoph Hellwig
2016-12-05 15:08 ` Jens Axboe
2016-12-03 3:15 ` [PATCH 3/7] block: use appropriate queue running functions Jens Axboe
2016-12-05 9:01 ` Johannes Thumshirn
2016-12-05 13:07 ` Christoph Hellwig
2016-12-05 15:10 ` Jens Axboe
2016-12-05 17:39 ` Jens Axboe
2016-12-03 3:15 ` [PATCH 4/7] blk-mq: blk_account_io_start() takes a bool Jens Axboe
2016-12-05 9:01 ` Johannes Thumshirn
2016-12-05 13:08 ` Christoph Hellwig
2016-12-03 3:15 ` [PATCH 5/7] blk-mq: test patch to get legacy IO schedulers working Jens Axboe
2016-12-03 3:15 ` [PATCH 6/7] block: drop irq+lock when flushing queue plugs Jens Axboe
2016-12-03 3:15 ` [PATCH 7/7] null_blk: add parameters to ask for mq-sched and write cache Jens Axboe
2016-12-03 4:02 ` [PATCHSET/RFC] Make legacy IO schedulers work with blk-mq Jens Axboe
2016-12-03 4:04 ` Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2016-12-05 18:26 [PATCHSET/RFC v2] " Jens Axboe
2016-12-05 18:27 ` [PATCH 1/7] block: use legacy path for flush requests for MQ with a scheduler Jens Axboe
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