lkml.org 
[lkml]   [2019]   [Oct]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] mm/rmap.c: reuse mergeable anon_vma as parent when fork
From
Date
On Sat, 2019-10-05 at 00:06 +0800, Wei Yang wrote:
> In function __anon_vma_prepare(), we will try to find anon_vma if it
> is
> possible to reuse it. While on fork, the logic is different.
>
> Since commit 5beb49305251 ("mm: change anon_vma linking to fix
> multi-process server scalability issue"), function anon_vma_clone()
> tries to allocate new anon_vma for child process. But the logic here
> will allocate a new anon_vma for each vma, even in parent this vma
> is mergeable and share the same anon_vma with its sibling. This may
> do
> better for scalability issue, while it is not necessary to do so
> especially after interval tree is used.
>
> Commit 7a3ef208e662 ("mm: prevent endless growth of anon_vma
> hierarchy")
> tries to reuse some anon_vma by counting child anon_vma and attached
> vmas. While for those mergeable anon_vmas, we can just reuse it and
> not
> necessary to go through the logic.
>
> After this change, kernel build test reduces 20% anon_vma allocation.
>
> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>

Acked-by: Rik van Riel <riel@surriel.com>

--
All Rights Reversed.
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2019-10-05 01:46    [W:0.077 / U:5.680 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site