lkml.org 
[lkml]   [2020]   [Jan]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] powerpc/32s: Don't flush all TLBs when flushing one page
On Fri, Jan 31, 2020 at 05:15:20PM +0100, Christophe Leroy wrote:
> Le 31/01/2020 à 16:51, Segher Boessenkool a écrit :
> >On Fri, Jan 31, 2020 at 03:37:34PM +0000, Christophe Leroy wrote:
> >>When the range is a single page, do a page flush instead.
> >
> >>+ start &= PAGE_MASK;
> >>+ end = (end - 1) | ~PAGE_MASK;
> >> if (!Hash) {
> >>- _tlbia();
> >>+ if (end - start == PAGE_SIZE)
> >>+ _tlbie(start);
> >>+ else
> >>+ _tlbia();
> >> return;
> >> }
> >
> >For just one page, you get end - start == 0 actually?
>
> Oops, good catch.
>
> Indeed you don't get PAGE_SIZE but (PAGE_SIZE - 1) for just one page.

You have all low bits masked off in both start and end, so you get zero.
You could make the condion read "if (start == end)?

Maybe a nicer way to describe what you do is "if start and end are on the
same memory page, flush that page."


Segher

\
 
 \ /
  Last update: 2020-01-31 20:39    [W:0.045 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site