From: Nikolay Borisov <nborisov@suse.com>
To: Tejun Heo <tj@kernel.org>,
clm@fb.com, David Sterba <dsterba@suse.com>,
josef@toxicpanda.com
Cc: kernel-team@fb.com, axboe@kernel.dk, jack@suse.cz,
linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/5] Btrfs: stop using btrfs_schedule_bio()
Date: Thu, 11 Jul 2019 14:32:20 +0300 [thread overview]
Message-ID: <4b4664f4-2f49-bc4b-bc29-be10fb19a3a2@suse.com> (raw)
In-Reply-To: <20190710192818.1069475-2-tj@kernel.org>
On 10.07.19 г. 22:28 ч., Tejun Heo wrote:
> From: Chris Mason <clm@fb.com>
>
> btrfs_schedule_bio() hands IO off to a helper thread to do the actual
> submit_bio() call. This has been used to make sure async crc and
> compression helpers don't get stuck on IO submission. To maintain good
> performance, over time the IO submission threads duplicated some IO
> scheduler characteristics such as high and low priority IOs and they
> also made some ugly assumptions about request allocation batch sizes.
>
> All of this cost at least one extra context switch during IO submission,
> and doesn't fit well with the modern blkmq IO stack. So, this commit stops
> using btrfs_schedule_bio(). We may need to adjust the number of async
> helper threads for crcs and compression, but long term it's a better
> path.
>
> Signed-off-by: Chris Mason <clm@fb.com>
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
<snip>
next prev parent reply other threads:[~2019-07-11 11:32 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-10 19:28 [PATCHSET v3 btrfs/for-next] btrfs: fix cgroup writeback support Tejun Heo
2019-07-10 19:28 ` [PATCH 1/5] Btrfs: stop using btrfs_schedule_bio() Tejun Heo
2019-07-11 11:32 ` Nikolay Borisov [this message]
2019-07-10 19:28 ` [PATCH 2/5] Btrfs: delete the entire async bio submission framework Tejun Heo
2019-07-11 14:53 ` Nikolay Borisov
2019-07-10 19:28 ` [PATCH 3/5] Btrfs: only associate the locked page with one async_cow struct Tejun Heo
2019-07-11 16:00 ` Nikolay Borisov
2019-07-11 19:52 ` Chris Mason
2019-07-26 15:29 ` Nikolay Borisov
2019-07-10 19:28 ` [PATCH 4/5] Btrfs: use REQ_CGROUP_PUNT for worker thread submitted bios Tejun Heo
2019-07-10 19:28 ` [PATCH 5/5] Btrfs: extent_write_locked_range() should attach inode->i_wb Tejun Heo
2019-07-26 15:13 ` [PATCHSET v3 btrfs/for-next] btrfs: fix cgroup writeback support David Sterba
2019-09-05 11:59 ` David Sterba
2019-09-06 17:46 ` Tejun Heo
2019-10-02 14:15 ` David Sterba
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