aboutsummaryrefslogtreecommitdiffstats
path: root/include/asm-i386/mmu_context.h
diff options
context:
space:
mode:
authorJeremy Fitzhardinge <jeremy@goop.org>2007-02-13 07:26:20 -0500
committerAndi Kleen <andi@basil.nowhere.org>2007-02-13 07:26:20 -0500
commit464d1a78fbf8cf6c7fd970e7b3e2db50a320ce28 (patch)
tree536d8a92976e675b484b35dec88d40c97fab8ac8 /include/asm-i386/mmu_context.h
parent54413927f022292aeccadd268fbf1c0b42129945 (diff)
[PATCH] i386: Convert i386 PDA code to use %fs
Convert the PDA code to use %fs rather than %gs as the segment for per-processor data. This is because some processors show a small but measurable performance gain for reloading a NULL segment selector (as %fs generally is in user-space) versus a non-NULL one (as %gs generally is). On modern processors the difference is very small, perhaps undetectable. Some old AMD "K6 3D+" processors are noticably slower when %fs is used rather than %gs; I have no idea why this might be, but I think they're sufficiently rare that it doesn't matter much. This patch also fixes the math emulator, which had not been adjusted to match the changed struct pt_regs. [frederik.deweerdt@gmail.com: fixit with gdb] [mingo@elte.hu: Fix KVM too] Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Andi Kleen <ak@suse.de> Cc: Ian Campbell <Ian.Campbell@XenSource.com> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Zachary Amsden <zach@vmware.com> Cc: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org>
Diffstat (limited to 'include/asm-i386/mmu_context.h')
-rw-r--r--include/asm-i386/mmu_context.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/asm-i386/mmu_context.h b/include/asm-i386/mmu_context.h
index 68ff102d6f5e..e6aa30f8de5b 100644
--- a/include/asm-i386/mmu_context.h
+++ b/include/asm-i386/mmu_context.h
@@ -63,7 +63,7 @@ static inline void switch_mm(struct mm_struct *prev,
63} 63}
64 64
65#define deactivate_mm(tsk, mm) \ 65#define deactivate_mm(tsk, mm) \
66 asm("movl %0,%%fs": :"r" (0)); 66 asm("movl %0,%%gs": :"r" (0));
67 67
68#define activate_mm(prev, next) \ 68#define activate_mm(prev, next) \
69 switch_mm((prev),(next),NULL) 69 switch_mm((prev),(next),NULL)