diff options
| author | Jeremy Fitzhardinge <jeremy@goop.org> | 2007-02-13 13:26:20 +0100 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2007-02-13 13:26:20 +0100 |
| commit | 464d1a78fbf8cf6c7fd970e7b3e2db50a320ce28 (patch) | |
| tree | 536d8a92976e675b484b35dec88d40c97fab8ac8 /include/asm-i386/processor.h | |
| parent | 54413927f022292aeccadd268fbf1c0b42129945 (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/processor.h')
| -rw-r--r-- | include/asm-i386/processor.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h index 359f10b54f5..11bf899de8a 100644 --- a/include/asm-i386/processor.h +++ b/include/asm-i386/processor.h @@ -424,7 +424,7 @@ struct thread_struct { .vm86_info = NULL, \ .sysenter_cs = __KERNEL_CS, \ .io_bitmap_ptr = NULL, \ - .gs = __KERNEL_PDA, \ + .fs = __KERNEL_PDA, \ } /* @@ -442,8 +442,8 @@ struct thread_struct { } #define start_thread(regs, new_eip, new_esp) do { \ - __asm__("movl %0,%%fs": :"r" (0)); \ - regs->xgs = 0; \ + __asm__("movl %0,%%gs": :"r" (0)); \ + regs->xfs = 0; \ set_fs(USER_DS); \ regs->xds = __USER_DS; \ regs->xes = __USER_DS; \ |