From: Jens Axboe <axboe@kernel.dk>
To: linux-block@vger.kernel.org
Subject: [PATCHSET 0/4] blk-mq: per-ctx tag caching
Date: Mon, 30 Dec 2019 11:14:39 -0700 [thread overview]
Message-ID: <20191230181442.4460-1-axboe@kernel.dk> (raw)
This is something I've been toying with yesterday, and got it cleaned
up a bit just now. It's still very much a testing thing, and there's a
few debug checks in there and items that need improving.
Anyway, the idea here is that we can reduce the cost of getting a tag
for a new request, if we don't get them piecemeal. Add a per-ctx tag
cache, and grab batches of tags if it's empty. If it's not empty, we
can just find a free bit there.
/sys/kernel/debug/block/<dev>/<hctx>/<cpu>/tag_hit holds some stats
associated with this, so you can check how it's doing.
I've seen nice improvements with this in testing.
--
Jens Axboe
next reply other threads:[~2019-12-30 18:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-30 18:14 Jens Axboe [this message]
2019-12-30 18:14 ` [PATCH 1/4] sbitmap: remove cleared bitmask Jens Axboe
2019-12-30 18:14 ` [PATCH 2/4] sbitmap: mask out top bits that can't be used Jens Axboe
2019-12-30 18:14 ` [PATCH 3/4] sbitmap: add batch tag retrieval Jens Axboe
2019-12-30 18:14 ` [PATCH 4/4] blk-mq: allocate tags in batches Jens Axboe
2019-12-31 2:18 ` Ming Lei
2019-12-31 3:53 ` Jens Axboe
2019-12-31 4:11 ` Jens Axboe
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