summaryrefslogtreecommitdiffhomepage
path: root/pkg
diff options
context:
space:
mode:
authorgVisor bot <gvisor-bot@google.com>2020-02-18 13:49:17 -0800
committergVisor bot <gvisor-bot@google.com>2020-02-18 13:50:07 -0800
commita3582de6186edcc88e022af2b9f9c1cef90e44ed (patch)
tree0c701f580e6da9dfe702ae290bf99b4c53b27ce8 /pkg
parent906eb6295d54a05663a223f1dc379a16148de2d1 (diff)
cpuid: cache the maximum size of xsave state
perf shows that ExtendedStateSize cosumes more than 20% of cpu: 23.61% 23.61% [.] pkg/cpuid/cpuid.HostID PiperOrigin-RevId: 295813263
Diffstat (limited to 'pkg')
-rw-r--r--pkg/cpuid/cpuid_x86.go19
1 files changed, 13 insertions, 6 deletions
diff --git a/pkg/cpuid/cpuid_x86.go b/pkg/cpuid/cpuid_x86.go
index 333ca0a04..a0bc55ea1 100644
--- a/pkg/cpuid/cpuid_x86.go
+++ b/pkg/cpuid/cpuid_x86.go
@@ -725,6 +725,18 @@ func vendorIDFromRegs(bx, cx, dx uint32) string {
return string(bytes)
}
+var maxXsaveSize = func() uint32 {
+ // Leaf 0 of xsaveinfo function returns the size for currently
+ // enabled xsave features in ebx, the maximum size if all valid
+ // features are saved with xsave in ecx, and valid XCR0 bits in
+ // edx:eax.
+ //
+ // If xSaveInfo isn't supported, cpuid will not fault but will
+ // return bogus values.
+ _, _, maxXsaveSize, _ := HostID(uint32(xSaveInfo), 0)
+ return maxXsaveSize
+}()
+
// ExtendedStateSize returns the number of bytes needed to save the "extended
// state" for this processor and the boundary it must be aligned to. Extended
// state includes floating point registers, and other cpu state that's not
@@ -736,12 +748,7 @@ func vendorIDFromRegs(bx, cx, dx uint32) string {
// about 2.5K worst case, with avx512).
func (fs *FeatureSet) ExtendedStateSize() (size, align uint) {
if fs.UseXsave() {
- // Leaf 0 of xsaveinfo function returns the size for currently
- // enabled xsave features in ebx, the maximum size if all valid
- // features are saved with xsave in ecx, and valid XCR0 bits in
- // edx:eax.
- _, _, maxSize, _ := HostID(uint32(xSaveInfo), 0)
- return uint(maxSize), 64
+ return uint(maxXsaveSize), 64
}
// If we don't support xsave, we fall back to fxsave, which requires