* [PATCH] powerpc: system call micro optimisation
@ 2006-06-10 15:15 Anton Blanchard
2006-06-10 22:24 ` Benjamin Herrenschmidt
0 siblings, 1 reply; 2+ messages in thread
From: Anton Blanchard @ 2006-06-10 15:15 UTC (permalink / raw)
To: linuxppc-dev; +Cc: paulus
In the syscall path we currently have:
crclr so
mfcr r9
If we shift the crclr up we can avoid a stall on some CPUs.
Signed-off-by: Anton Blanchard <anton@samba.org>
---
Index: kernel/arch/powerpc/kernel/entry_64.S
===================================================================
--- kernel.orig/arch/powerpc/kernel/entry_64.S 2006-04-26 08:03:05.380651922 -0500
+++ kernel/arch/powerpc/kernel/entry_64.S 2006-04-26 08:03:28.076523958 -0500
@@ -59,6 +59,7 @@ system_call_common:
beq- 1f
ld r1,PACAKSAVE(r13)
1: std r10,0(r1)
+ crclr so
std r11,_NIP(r1)
std r12,_MSR(r1)
std r0,GPR0(r1)
@@ -77,7 +78,6 @@ system_call_common:
std r11,GPR11(r1)
std r11,GPR12(r1)
std r9,GPR13(r1)
- crclr so
mfcr r9
mflr r10
li r11,0xc01
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] powerpc: system call micro optimisation
2006-06-10 15:15 [PATCH] powerpc: system call micro optimisation Anton Blanchard
@ 2006-06-10 22:24 ` Benjamin Herrenschmidt
0 siblings, 0 replies; 2+ messages in thread
From: Benjamin Herrenschmidt @ 2006-06-10 22:24 UTC (permalink / raw)
To: Anton Blanchard; +Cc: linuxppc-dev, paulus
On Sun, 2006-06-11 at 01:15 +1000, Anton Blanchard wrote:
> In the syscall path we currently have:
>
> crclr so
> mfcr r9
>
> If we shift the crclr up we can avoid a stall on some CPUs.
Can you maybe have a quick look at the vDSO's ? They might have similar
room for optimisations...
Cheers,
Ben.
> Signed-off-by: Anton Blanchard <anton@samba.org>
> ---
>
> Index: kernel/arch/powerpc/kernel/entry_64.S
> ===================================================================
> --- kernel.orig/arch/powerpc/kernel/entry_64.S 2006-04-26 08:03:05.380651922 -0500
> +++ kernel/arch/powerpc/kernel/entry_64.S 2006-04-26 08:03:28.076523958 -0500
> @@ -59,6 +59,7 @@ system_call_common:
> beq- 1f
> ld r1,PACAKSAVE(r13)
> 1: std r10,0(r1)
> + crclr so
> std r11,_NIP(r1)
> std r12,_MSR(r1)
> std r0,GPR0(r1)
> @@ -77,7 +78,6 @@ system_call_common:
> std r11,GPR11(r1)
> std r11,GPR12(r1)
> std r9,GPR13(r1)
> - crclr so
> mfcr r9
> mflr r10
> li r11,0xc01
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-dev
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2006-06-10 22:25 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2006-06-10 15:15 [PATCH] powerpc: system call micro optimisation Anton Blanchard
2006-06-10 22:24 ` Benjamin Herrenschmidt
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).