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| author | mav <mav@FreeBSD.org> | 2015-03-30 07:11:49 +0000 |
|---|---|---|
| committer | mav <mav@FreeBSD.org> | 2015-03-30 07:11:49 +0000 |
| commit | 3e11976044f532ef483da0eb314ce7957b524c5f (patch) | |
| tree | 401706755b4e541d3706c33ec9c794f3b4be812a /sys/amd64/vmm | |
| parent | 1d0629a91fc375755679aae4979d143430e2aff6 (diff) | |
| download | FreeBSD-src-3e11976044f532ef483da0eb314ce7957b524c5f.zip FreeBSD-src-3e11976044f532ef483da0eb314ce7957b524c5f.tar.gz | |
MFC r280134:
Report ARAT (APIC-Timer-always-running) feature for virtual CPU.
This makes FreeBSD guest to not avoid using LAPIC timer, preferring HPET
due to worries about non-existing for virtual CPUs deep sleep states.
Benchmarks of usleep(1) on guest and host show such extra latencies:
- 51us for virtual HPET,
- 22us for virtual LAPIC timer,
- 22us for host HPET and
- 3us for host LAPIC timer.
Diffstat (limited to 'sys/amd64/vmm')
| -rw-r--r-- | sys/amd64/vmm/x86.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/sys/amd64/vmm/x86.c b/sys/amd64/vmm/x86.c index c0c3e9c..c37d21c 100644 --- a/sys/amd64/vmm/x86.c +++ b/sys/amd64/vmm/x86.c @@ -361,6 +361,12 @@ x86_emulate_cpuid(struct vm *vm, int vcpu_id, break; case CPUID_0000_0006: + regs[0] = CPUTPM1_ARAT; + regs[1] = 0; + regs[2] = 0; + regs[3] = 0; + break; + case CPUID_0000_000A: /* * Handle the access, but report 0 for |
