From: Anton Blanchard <anton@samba.org>
To: linuxppc-dev@ozlabs.org
Cc: paulus@samba.org
Subject: [PATCH] powerpc: system call micro optimisation
Date: Sun, 11 Jun 2006 01:15:55 +1000 [thread overview]
Message-ID: <20060610151555.GV23891@krispykreme> (raw)
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
next reply other threads:[~2006-06-10 15:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-10 15:15 Anton Blanchard [this message]
2006-06-10 22:24 ` [PATCH] powerpc: system call micro optimisation Benjamin Herrenschmidt
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