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Subject[PATCH -mm] i386: cpu_relax() smp.c (was: [RFC -mm] more cpu_relax() places?)
Hi,

On Mon, Jun 12, 2006 at 08:37:43PM +0200, Andreas Mohr wrote:
> Hi all,
>
> while reviewing 2.6.17-rc6-mm1, I found some places that might
> want to make use of cpu_relax() in order to not block secondary
> pipelines while busy-polling (probably especially useful on SMT CPUs):

OK, no replies arguing against anything, thus patch follow-up. ;)
(no. 1 of 3)

Signed-off-by: Andreas Mohr <andi@lisas.de>


diff -urN linux-2.6.17-rc6-mm2.orig/arch/i386/kernel/smp.c linux-2.6.17-rc6-mm2.my/arch/i386/kernel/smp.c
--- linux-2.6.17-rc6-mm2.orig/arch/i386/kernel/smp.c 2006-06-08 10:38:04.000000000 +0200
+++ linux-2.6.17-rc6-mm2.my/arch/i386/kernel/smp.c 2006-06-13 19:33:22.000000000 +0200
@@ -388,9 +388,11 @@
*/
send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR);

- while (!cpus_empty(flush_cpumask))
+ while (!cpus_empty(flush_cpumask)) {
+ cpu_relax();
/* nothing. lockup detection does not belong here */
mb();
+ }

flush_mm = NULL;
flush_va = 0;
-
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