From: Christoph Hellwig <hch@infradead.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 2/2] mm: Use clear_bit_unlock_is_negative_byte for PageWriteback
Date: Thu, 26 Mar 2020 10:11:14 -0700 [thread overview]
Message-ID: <20200326171114.GA6566@infradead.org> (raw)
In-Reply-To: <20200326122429.20710-3-willy@infradead.org>
On Thu, Mar 26, 2020 at 05:24:29AM -0700, Matthew Wilcox wrote:
> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
>
> By moving PG_writeback down into the low bits of the page flags, we can
> use clear_bit_unlock_is_negative_byte() for writeback as well as the
> lock bit. wake_up_page() then has no more callers. Given the other
> code being executed between the clear and the test, this is not going
> to be as dramatic a win as it was for PageLocked, but symmetry between
> the two is nice and lets us remove some code.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
> include/linux/page-flags.h | 6 +++---
> mm/filemap.c | 19 ++++++-------------
> mm/page-writeback.c | 37 ++++++++++++++++++++-----------------
> 3 files changed, 29 insertions(+), 33 deletions(-)
>
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index 222f6f7b2bb3..96c7d220c8cf 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -103,13 +103,14 @@
> */
> enum pageflags {
> PG_locked, /* Page is locked. Don't touch. */
> + PG_writeback, /* Page is under writeback */
Do we need a comment why these need to be in the low bits?
next prev parent reply other threads:[~2020-03-26 17:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-26 12:24 [PATCH 0/2] Make PageWriteback use the PageLocked optimisation Matthew Wilcox
2020-03-26 12:24 ` [PATCH 1/2] mm: Remove definition of clear_bit_unlock_is_negative_byte Matthew Wilcox
2020-04-16 12:45 ` Will Deacon
2020-04-16 14:31 ` Matthew Wilcox
2020-03-26 12:24 ` [PATCH 2/2] mm: Use clear_bit_unlock_is_negative_byte for PageWriteback Matthew Wilcox
2020-03-26 12:40 ` Jan Kara
2020-03-26 12:44 ` Matthew Wilcox
2020-03-27 10:46 ` William Kucharski
2020-03-26 17:11 ` Christoph Hellwig [this message]
2020-03-26 17:16 ` Matthew Wilcox
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