lkml.org 
[lkml]   [2021]   [Jan]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] mm: Free unused swap cache page in write protection fault handler
On Wed, Jan 13, 2021 at 11:08:56AM +0800, huang ying wrote:
> On Wed, Jan 13, 2021 at 10:47 AM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > On Tue, Jan 12, 2021 at 6:43 PM Huang Ying <ying.huang@intel.com> wrote:
> > >
> > > So in this patch, at the end of wp_page_copy(), the old unused swap
> > > cache page will be tried to be freed.
> >
> > I'd much rather free it later when needed, rather than when you're in
> > a COW section.
>
> Unused swap cache isn't unused file cache. Nobody can reuse them
> directly before freeing them firstly. It will make COW a little
> faster via keeping them. But I think the overhead to free them isn't
> high. While keeping them in system will confuse users (users will
> expect file cache to use free memory, but not expect unused swap cache
> to use much free memory), make the swap space more fragmented, and add
> system overall overhead (scanning LRU list, etc.).

Couldn't we just move it to the tail of the LRU list so it's reclaimed
first? Or is locking going to be a problem here?

\
 
 \ /
  Last update: 2021-01-13 04:14    [W:0.068 / U:0.264 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site