From: Jens Axboe <axboe@kernel.dk>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>
Subject: Re: [PATCH 10/12] writeback: only allow one inflight and pending full flush
Date: Fri, 29 Sep 2017 02:17:32 +0200 [thread overview]
Message-ID: <552d4502-0b0a-87fc-7b16-6b322c3af3ed@kernel.dk> (raw)
In-Reply-To: <CA+55aFw14cHWfcqi_4HpMserCDLX97kbnV2X+L+fio3wRHpkig@mail.gmail.com>
On 09/28/2017 11:44 PM, Linus Torvalds wrote:
> On Thu, Sep 28, 2017 at 2:41 PM, Andrew Morton
> <akpm@linux-foundation.org> wrote:
>>
>> test_and_set_bit()?
>
> If there aren't any atomicity concerns (either because of higher-level
> locking, or because racing and having two people set the bit is fine),
> it can be better to do them separately if the test_bit() is the common
> case and you can avoid dirtying a cacheline that way.
>
> But yeah, if that is the case, it might be worth documenting, because
> test_and_set_bit() is the more obviously appropriate "there can be
> only one" model.
It is documented though, but maybe not well enough...
I've actually had to document/explain it enough times now, that it
might be worth making a general construct. Though it has to be
used carefully, so perhaps it's better contained as separate use
cases.
--
Jens Axboe
next prev parent reply other threads:[~2017-09-29 0:17 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-27 20:13 [PATCH 0/12 v3] Writeback improvements Jens Axboe
2017-09-27 20:13 ` [PATCH 01/12] buffer: have alloc_page_buffers() use __GFP_NOFAIL Jens Axboe
2017-09-28 14:08 ` Nikolay Borisov
2017-10-02 15:02 ` Jan Kara
2017-09-27 20:13 ` [PATCH 02/12] buffer: grow_dev_page() should use __GFP_NOFAIL for all cases Jens Axboe
2017-09-28 14:11 ` Nikolay Borisov
2017-09-28 18:12 ` Jens Axboe
2017-10-03 12:10 ` Jan Kara
2017-10-03 12:25 ` Jan Kara
2017-10-03 14:36 ` Jens Axboe
2017-10-03 15:52 ` Jan Kara
2017-09-27 20:13 ` [PATCH 03/12] buffer: eliminate the need to call free_more_memory() in __getblk_slow() Jens Axboe
2017-09-28 14:12 ` Nikolay Borisov
2017-10-03 12:22 ` Jan Kara
2017-09-27 20:13 ` [PATCH 04/12] fs: kill 'nr_pages' argument from wakeup_flusher_threads() Jens Axboe
2017-09-27 20:13 ` [PATCH 05/12] writeback: switch wakeup_flusher_threads() to cyclic writeback Jens Axboe
2017-10-03 12:43 ` Jan Kara
2017-09-27 20:13 ` [PATCH 06/12] writeback: provide a wakeup_flusher_threads_bdi() Jens Axboe
2017-09-27 20:13 ` [PATCH 07/12] writeback: pass in '0' for nr_pages writeback in laptop mode Jens Axboe
2017-09-27 20:13 ` [PATCH 08/12] writeback: make wb_start_writeback() static Jens Axboe
2017-09-27 20:13 ` [PATCH 09/12] writeback: move nr_pages == 0 logic to one location Jens Axboe
2017-09-27 20:13 ` [PATCH 10/12] writeback: only allow one inflight and pending full flush Jens Axboe
2017-09-28 21:41 ` Andrew Morton
2017-09-28 21:44 ` Linus Torvalds
2017-09-29 0:17 ` Jens Axboe [this message]
2017-09-29 5:21 ` Amir Goldstein
2017-10-03 16:06 ` Matthew Wilcox
2017-10-03 16:11 ` Jens Axboe
2017-10-03 17:03 ` Matthew Wilcox
2017-09-29 0:15 ` Jens Axboe
2017-09-27 20:13 ` [PATCH 11/12] writeback: make sync_inodes_sb() use range cyclic writeback Jens Axboe
2017-09-27 20:13 ` [PATCH 12/12] writeback: kill off ->range_cycle option Jens Axboe
2017-09-27 20:22 ` Jens Axboe
2017-09-28 13:19 ` [PATCH 0/12 v3] Writeback improvements John Stoffel
2017-09-28 13:39 ` Jens Axboe
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