diff options
| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2019-08-22 11:36:30 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-08-23 17:59:54 +0300 |
| commit | 3e2d94535adb2df15f3907e4b4c7cd8a5a4c2b5a (patch) | |
| tree | aa53940e9cf060d6afd783cdaeea0a998101722a /arch/x86/include/asm/vdso | |
| parent | bd00cd52d5be655a2f217e2ed74b91a71cb2b14f (diff) | |
| download | linux-3e2d94535adb2df15f3907e4b4c7cd8a5a4c2b5a.tar.xz | |
clocksource/drivers/hyperv: Enable TSC page clocksource on 32bit
There is no particular reason to not enable TSC page clocksource on
32-bit. mul_u64_u64_shr() is available and despite the increased
computational complexity (compared to 64bit) TSC page is still a huge win
compared to MSR-based clocksource.
In-kernel reads:
MSR based clocksource: 3361 cycles
TSC page clocksource: 49 cycles
Reads from userspace (utilizing vDSO in case of TSC page):
MSR based clocksource: 5664 cycles
TSC page clocksource: 131 cycles
Enabling TSC page on 32bits allows to get rid of CONFIG_HYPERV_TSCPAGE as
it is now not any different from CONFIG_HYPERV_TIMER.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lkml.kernel.org/r/20190822083630.17059-1-vkuznets@redhat.com
Diffstat (limited to 'arch/x86/include/asm/vdso')
| -rw-r--r-- | arch/x86/include/asm/vdso/gettimeofday.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h index ae91429129a6..bcbf901befbe 100644 --- a/arch/x86/include/asm/vdso/gettimeofday.h +++ b/arch/x86/include/asm/vdso/gettimeofday.h @@ -51,7 +51,7 @@ extern struct pvclock_vsyscall_time_info pvclock_page __attribute__((visibility("hidden"))); #endif -#ifdef CONFIG_HYPERV_TSCPAGE +#ifdef CONFIG_HYPERV_TIMER extern struct ms_hyperv_tsc_page hvclock_page __attribute__((visibility("hidden"))); #endif @@ -192,7 +192,7 @@ static u64 vread_pvclock(void) } #endif -#ifdef CONFIG_HYPERV_TSCPAGE +#ifdef CONFIG_HYPERV_TIMER static u64 vread_hvclock(void) { return hv_read_tsc_page(&hvclock_page); @@ -215,7 +215,7 @@ static inline u64 __arch_get_hw_counter(s32 clock_mode) return vread_pvclock(); } #endif -#ifdef CONFIG_HYPERV_TSCPAGE +#ifdef CONFIG_HYPERV_TIMER if (clock_mode == VCLOCK_HVCLOCK) { barrier(); return vread_hvclock(); |