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author | gVisor bot <gvisor-bot@google.com> | 2020-02-18 13:49:17 -0800 |
---|---|---|
committer | gVisor bot <gvisor-bot@google.com> | 2020-02-18 13:50:07 -0800 |
commit | a3582de6186edcc88e022af2b9f9c1cef90e44ed (patch) | |
tree | 0c701f580e6da9dfe702ae290bf99b4c53b27ce8 /pkg | |
parent | 906eb6295d54a05663a223f1dc379a16148de2d1 (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.go | 19 |
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 |