From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: George Spelvin <linux@horizon.com>
Cc: ebiggers3@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: Bloat caused by unnecessary calls to compound_head()?
Date: Sun, 27 Mar 2016 23:44:13 +0300 [thread overview]
Message-ID: <20160327204413.GB9638@node.shutemov.name> (raw)
In-Reply-To: <20160327203304.9695.qmail@ns.horizon.com>
On Sun, Mar 27, 2016 at 04:33:04PM -0400, George Spelvin wrote:
> Could you just mark compound_head __pure? That would tell the compiler
> that it's safe to re-use the return value as long as there is no memory
> mutation in between.
>
Hm. It has some positive impact, but it's not dramatic. For instance,
mm/swap.o results:
add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-43 (-43)
function old new delta
__page_cache_release 319 298 -21
release_pages 722 700 -22
mark_page_accessed() problem was not fixed by that.
--
Kirill A. Shutemov
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WARNING: multiple messages have this Message-ID (diff)
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: George Spelvin <linux@horizon.com>
Cc: ebiggers3@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: Bloat caused by unnecessary calls to compound_head()?
Date: Sun, 27 Mar 2016 23:44:13 +0300 [thread overview]
Message-ID: <20160327204413.GB9638@node.shutemov.name> (raw)
In-Reply-To: <20160327203304.9695.qmail@ns.horizon.com>
On Sun, Mar 27, 2016 at 04:33:04PM -0400, George Spelvin wrote:
> Could you just mark compound_head __pure? That would tell the compiler
> that it's safe to re-use the return value as long as there is no memory
> mutation in between.
>
Hm. It has some positive impact, but it's not dramatic. For instance,
mm/swap.o results:
add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-43 (-43)
function old new delta
__page_cache_release 319 298 -21
release_pages 722 700 -22
mark_page_accessed() problem was not fixed by that.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2016-03-27 20:44 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-27 20:33 Bloat caused by unnecessary calls to compound_head()? George Spelvin
2016-03-27 20:33 ` George Spelvin
2016-03-27 20:44 ` Kirill A. Shutemov [this message]
2016-03-27 20:44 ` Kirill A. Shutemov
-- strict thread matches above, loose matches on Subject: below --
2016-03-26 18:50 Eric Biggers
2016-03-26 18:50 ` Eric Biggers
2016-03-27 19:46 ` Kirill A. Shutemov
2016-03-27 19:46 ` Kirill A. Shutemov
2016-04-01 1:33 ` Eric Biggers
2016-04-01 1:33 ` Eric Biggers
2016-04-04 10:39 ` Kirill A. Shutemov
2016-04-04 10:39 ` Kirill A. Shutemov
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