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authorJeremy Fitzhardinge <jeremy@goop.org>2007-02-13 13:26:20 +0100
committerAndi Kleen <andi@basil.nowhere.org>2007-02-13 13:26:20 +0100
commit464d1a78fbf8cf6c7fd970e7b3e2db50a320ce28 (patch)
tree536d8a92976e675b484b35dec88d40c97fab8ac8 /drivers/kvm
parent54413927f022292aeccadd268fbf1c0b42129945 (diff)
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[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 'drivers/kvm')
-rw-r--r--drivers/kvm/vmx.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 1e640b8..fd4e917 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1879,12 +1879,6 @@ again:
asm ("mov %0, %%ds; mov %0, %%es" : : "r"(__USER_DS));
- /*
- * Profile KVM exit RIPs:
- */
- if (unlikely(prof_on == KVM_PROFILING))
- profile_hit(KVM_PROFILING, (void *)vmcs_readl(GUEST_RIP));
-
kvm_run->exit_type = 0;
if (fail) {
kvm_run->exit_type = KVM_EXIT_TYPE_FAIL_ENTRY;
@@ -1907,6 +1901,12 @@ again:
reload_tss();
}
+ /*
+ * Profile KVM exit RIPs:
+ */
+ if (unlikely(prof_on == KVM_PROFILING))
+ profile_hit(KVM_PROFILING, (void *)vmcs_readl(GUEST_RIP));
+
vcpu->launched = 1;
kvm_run->exit_type = KVM_EXIT_TYPE_VM_EXIT;
r = kvm_handle_exit(kvm_run, vcpu);