lkml.org 
[lkml]   [2004]   [May]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] rmap 24 pte_young first
On Sat, May 08, 2004 at 11:39:32PM +0100, Hugh Dickins wrote:
> rmap 25 of course
>
> On Sat, 8 May 2004, Christoph Hellwig wrote:
> > On Sat, May 08, 2004 at 10:56:26PM +0100, Hugh Dickins wrote:
> > >
> > > - if (ptep_test_and_clear_young(pte))
> > > + if (pte_young(*pte) && ptep_test_and_clear_young(pte))
> >
> > stupid question - shouldn't the pte_young check simply move to
> > the beginning of ptep_test_and_clear_young?
>
> I don't think that would be a good idea. We're used to those
> test_and_clear operations being atomic, putting an initial non-atomic
> test inside would make it fundamentally non-atomic. We know here that
> it's not the end of the world if we miss a racing transition of the
> young bit, but it wouldn't be good to hide and force that on others.

EAGAIN.

include/asm-generic/pgtable.h:

#ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
static inline int ptep_test_and_clear_young(pte_t *ptep)
{
pte_t pte = *ptep;
if (!pte_young(pte))
return 0;
set_pte(ptep, pte_mkold(pte));
return 1;
}
#endif


--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:03    [W:0.046 / U:0.256 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site