lkml.org 
[lkml]   [2013]   [May]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 01/02] swap: discard while swapping only if SWAP_FLAG_DISCARD_PAGES
On Sun, May 26, 2013 at 07:44:56AM -0400, KOSAKI Motohiro wrote:
> > + /*
> > + * By flagging sys_swapon, a sysadmin can tell us to
> > + * either do sinle-time area discards only, or to just
> > + * perform discards for released swap page-clusters.
> > + * Now it's time to adjust the p->flags accordingly.
> > + */
> > + if (swap_flags & SWAP_FLAG_DISCARD_ONCE)
> > + p->flags &= ~SWP_PAGE_DISCARD;
> > + else if (swap_flags & SWAP_FLAG_DISCARD_PAGES)
> > + p->flags &= ~SWP_AREA_DISCARD;
>
> When using old swapon(8), this code turn off both flags, right?

As the flag that enables swap discards SWAP_FLAG_DISCARD remains meaning the
same it meant before, when using old swapon(8) (SWP_PAGE_DISCARD|SWP_AREA_DISCARD)
will remain flagged when discard is enabled, so we keep doing discards the same way
we did before (at swapon, and for every released page-cluster).
The flags are removed orthogonally only when the new swapon(8) selects one of the
particular discard policy available by using either SWAP_FLAG_DISCARD_ONCE,
or SWAP_FLAG_DISCARD_PAGES flags.



\
 
 \ /
  Last update: 2013-05-26 16:41    [W:9.342 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site