From: Jens Axboe <axboe@kernel.dk>
To: Gabriel Krisman Bertazi <krisman@suse.de>
Cc: Hugh Dickins <hughd@google.com>, Keith Busch <kbusch@kernel.org>,
Jan Kara <jack@suse.cz>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
Liu Song <liusong@linux.alibaba.com>
Subject: Re: [PATCH] sbitmap: Use single per-bitmap counting to wake up queued tags
Date: Fri, 11 Nov 2022 08:38:51 -0700 [thread overview]
Message-ID: <166818113152.9209.17718783188573289588.b4-ty@kernel.dk> (raw)
In-Reply-To: <20221105231055.25953-1-krisman@suse.de>
On Sat, 5 Nov 2022 19:10:55 -0400, Gabriel Krisman Bertazi wrote:
> sbitmap suffers from code complexity, as demonstrated by recent fixes,
> and eventual lost wake ups on nested I/O completion. The later happens,
> from what I understand, due to the non-atomic nature of the updates to
> wait_cnt, which needs to be subtracted and eventually reset when equal
> to zero. This two step process can eventually miss an update when a
> nested completion happens to interrupt the CPU in between the wait_cnt
> updates. This is very hard to fix, as shown by the recent changes to
> this code.
>
> [...]
Applied, thanks!
[1/1] sbitmap: Use single per-bitmap counting to wake up queued tags
commit: 4f8126bb2308066b877859e4b5923ffb54143630
Best regards,
--
Jens Axboe
next prev parent reply other threads:[~2022-11-11 15:38 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-05 23:10 Gabriel Krisman Bertazi
2022-11-08 23:28 ` Chaitanya Kulkarni
2022-11-09 3:03 ` Gabriel Krisman Bertazi
2022-11-09 3:35 ` Chaitanya Kulkarni
2022-11-09 22:06 ` Jens Axboe
2022-11-09 22:48 ` Gabriel Krisman Bertazi
2022-11-10 3:25 ` Jens Axboe
2022-11-10 9:42 ` Yu Kuai
2022-11-10 11:16 ` Jan Kara
2022-11-10 13:18 ` Yu Kuai
2022-11-10 15:35 ` Jan Kara
2022-11-11 0:59 ` Yu Kuai
2022-11-11 15:38 ` Jens Axboe [this message]
2022-11-14 13:23 ` Jan Kara
2022-11-14 14:20 ` [PATCH] sbitmap: Advance the queue index before waking up the queue Gabriel Krisman Bertazi
2022-11-14 14:34 ` Jan Kara
2022-11-15 3:52 ` [PATCH] sbitmap: Use single per-bitmap counting to wake up queued tags Gabriel Krisman Bertazi
2022-11-15 10:24 ` Jan Kara
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