From: Jens Axboe <[email protected]>
To: Matthew Wilcox <[email protected]>
Cc: [email protected], [email protected],
[email protected], [email protected],
[email protected]
Subject: Re: [PATCH 04/12] mm: add support for async page locking
Date: Mon, 1 Jun 2020 11:15:22 -0600 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 6/1/20 8:26 AM, Matthew Wilcox wrote:
> On Tue, May 26, 2020 at 01:51:15PM -0600, Jens Axboe wrote:
>> +static int __wait_on_page_locked_async(struct page *page,
>> + struct wait_page_queue *wait, bool set)
>> +{
>> + struct wait_queue_head *q = page_waitqueue(page);
>> + int ret = 0;
>> +
>> + wait->page = page;
>> + wait->bit_nr = PG_locked;
>> +
>> + spin_lock_irq(&q->lock);
>> + if (set)
>> + ret = !trylock_page(page);
>> + else
>> + ret = PageLocked(page);
>> + if (ret) {
>> + __add_wait_queue_entry_tail(q, &wait->wait);
>> + SetPageWaiters(page);
>> + if (set)
>> + ret = !trylock_page(page);
>> + else
>> + ret = PageLocked(page);
>
> Between the callers and this function, we actually look at PG_lock three
> times; once in the caller, then after taking the spinlock, then after
> adding ourselves to the waitqueue. I understand the first and third, but
> is it really worth doing the second test? It feels unlikely to succeed
> and only saves us setting PageWaiters.
That's probably true, and we can skip the 2nd one. I'll make the change.
--
Jens Axboe
next prev parent reply other threads:[~2020-06-01 17:15 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-26 19:51 [PATCHSET v5 0/12] Add support for async buffered reads Jens Axboe
2020-05-26 19:51 ` [PATCH 01/12] block: read-ahead submission should imply no-wait as well Jens Axboe
2020-05-26 19:51 ` [PATCH 02/12] mm: allow read-ahead with IOCB_NOWAIT set Jens Axboe
2020-05-26 20:45 ` Johannes Weiner
2020-05-26 19:51 ` [PATCH 03/12] mm: abstract out wake_page_match() from wake_page_function() Jens Axboe
2020-05-26 21:02 ` Johannes Weiner
2020-06-01 14:16 ` Matthew Wilcox
2020-05-26 19:51 ` [PATCH 04/12] mm: add support for async page locking Jens Axboe
2020-05-26 21:59 ` Johannes Weiner
2020-05-26 22:01 ` Jens Axboe
2020-05-27 16:02 ` Johannes Weiner
2020-06-01 14:26 ` Matthew Wilcox
2020-06-01 17:15 ` Jens Axboe [this message]
2020-05-26 19:51 ` [PATCH 05/12] mm: support async buffered reads in generic_file_buffered_read() Jens Axboe
2020-05-26 22:00 ` Johannes Weiner
2020-05-26 19:51 ` [PATCH 06/12] fs: add FMODE_BUF_RASYNC Jens Axboe
2020-05-26 19:51 ` [PATCH 07/12] ext4: flag as supporting buffered async reads Jens Axboe
2020-05-26 19:51 ` [PATCH 08/12] block: flag block devices as supporting IOCB_WAITQ Jens Axboe
2020-05-26 19:51 ` [PATCH 09/12] xfs: flag files as supporting buffered async reads Jens Axboe
2020-05-28 17:53 ` Darrick J. Wong
2020-05-28 19:23 ` Jens Axboe
2020-05-26 19:51 ` [PATCH 10/12] btrfs: " Jens Axboe
2020-05-26 19:57 ` Chris Mason
2020-05-26 19:51 ` [PATCH 11/12] mm: add kiocb_wait_page_queue_init() helper Jens Axboe
2020-05-26 22:01 ` Johannes Weiner
2020-05-26 19:51 ` [PATCH 12/12] io_uring: support true async buffered reads, if file provides it Jens Axboe
[not found] ` <CA+icZUWfX+QmroE6j74C7o-BdfMF5=6PdYrA=5W_JCKddqkJgQ@mail.gmail.com>
2020-05-28 17:06 ` [PATCHSET v5 0/12] Add support for async buffered reads Jens Axboe
2020-05-28 17:12 ` Sedat Dilek
2020-05-28 17:14 ` Jens Axboe
2020-05-28 18:20 ` Sedat Dilek
2020-05-29 10:02 ` Sedat Dilek
2020-05-29 11:22 ` Sedat Dilek
2020-05-30 13:36 ` Sedat Dilek
2020-05-30 18:57 ` Sedat Dilek
2020-05-31 1:57 ` Jens Axboe
[not found] ` <CA+icZUXxmOA-5+dukCgxfSp4eVHB+QaAHO6tsgq0iioQs3Af-w@mail.gmail.com>
2020-05-31 7:12 ` Sedat Dilek
2020-06-01 13:35 ` Sedat Dilek
2020-06-01 14:04 ` Jens Axboe
2020-06-01 14:13 ` Sedat Dilek
2020-06-01 14:14 ` Jens Axboe
2020-06-01 14:35 ` Jens Axboe
2020-06-01 14:43 ` Sedat Dilek
2020-06-01 14:46 ` Jens Axboe
2020-06-01 14:51 ` Sedat Dilek
2020-06-01 20:18 ` Sedat Dilek
[not found] ` <[email protected]>
2020-06-04 1:04 ` Jens Axboe
2020-06-04 1:30 ` Andres Freund
2020-06-05 19:56 ` Andres Freund
2020-06-05 14:42 ` Jens Axboe
2020-06-05 20:20 ` Andres Freund
2020-06-05 20:21 ` Jens Axboe
2020-06-05 20:36 ` Andres Freund
2020-06-05 20:53 ` Jens Axboe
2020-06-05 21:13 ` Jens Axboe
2020-06-05 21:21 ` Jens Axboe
2020-06-05 22:30 ` Andres Freund
2020-06-05 22:36 ` Andres Freund
2020-06-05 22:49 ` Jens Axboe
2020-06-05 22:54 ` Andres Freund
2020-06-05 22:56 ` Jens Axboe
2020-06-05 23:02 ` Andres Freund
2020-06-06 0:33 ` Sedat Dilek
2020-06-06 16:04 ` Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2020-05-24 19:21 [PATCHSET v4 " Jens Axboe
2020-05-24 19:21 ` [PATCH 04/12] mm: add support for async page locking Jens Axboe
2020-05-23 18:57 [PATCHSET v2 0/12] Add support for async buffered reads Jens Axboe
2020-05-23 18:57 ` [PATCH 04/12] mm: add support for async page locking Jens Axboe
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