[PATCH v2] x86/hyper-v: enable TSC page clocksource on 32bit
STALE2596d
REVIEWED: 1 (0M)
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: 2019-08-22 08:36:37
Also in:
lkml
Subsystem:
clocksource, clockevent drivers, hyper-v/azure core and drivers, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Daniel Lezcano, Thomas Gleixner, "K. Y. Srinivasan", Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Linus Torvalds, Ingo Molnar, Borislav Petkov, Dave Hansen
1 review trailer.
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. Reviewed-by: Michael Kelley <redacted> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> --- Changes since v1: - Fix a couple of nits in changelog [Michael Kelley, Thomas Gleixner] - Fixed a comment with CONFIG_HYPERV_TSC_PAGE [Michael Kelley] - Added Michael's Reviewed-by: tag - Rebased on timers/core [Thomas Gleixner] --- arch/x86/include/asm/vdso/gettimeofday.h | 6 +++--- drivers/clocksource/hyperv_timer.c | 11 ----------- drivers/hv/Kconfig | 3 --- include/clocksource/hyperv_timer.h | 8 +++----- 4 files changed, 6 insertions(+), 22 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();
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index dad8af198e20..51b4d7ba959c 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c@@ -212,8 +212,6 @@ EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup); struct clocksource *hyperv_cs; EXPORT_SYMBOL_GPL(hyperv_cs); -#ifdef CONFIG_HYPERV_TSCPAGE - static struct ms_hyperv_tsc_page tsc_pg __aligned(PAGE_SIZE); static u64 hv_sched_clock_offset __ro_after_init;
@@ -245,7 +243,6 @@ static struct clocksource hyperv_cs_tsc = { .mask = CLOCKSOURCE_MASK(64), .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; -#endif static u64 notrace read_hv_clock_msr(struct clocksource *arg) {
@@ -272,7 +269,6 @@ static struct clocksource hyperv_cs_msr = { .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; -#ifdef CONFIG_HYPERV_TSCPAGE static bool __init hv_init_tsc_clocksource(void) { u64 tsc_msr;
@@ -304,13 +300,6 @@ static bool __init hv_init_tsc_clocksource(void) return true; } -#else -static bool __init hv_init_tsc_clocksource(void) -{ - return false; -} -#endif - void __init hv_init_clocksource(void) {
diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 9a59957922d4..79e5356a737a 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig@@ -14,9 +14,6 @@ config HYPERV config HYPERV_TIMER def_bool HYPERV -config HYPERV_TSCPAGE - def_bool HYPERV && X86_64 - config HYPERV_UTILS tristate "Microsoft Hyper-V Utilities driver" depends on HYPERV && CONNECTOR && NLS
diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h
index a821deb8ecb2..422f5e5237be 100644
--- a/include/clocksource/hyperv_timer.h
+++ b/include/clocksource/hyperv_timer.h@@ -28,12 +28,10 @@ extern void hv_stimer_cleanup(unsigned int cpu); extern void hv_stimer_global_cleanup(void); extern void hv_stimer0_isr(void); -#if IS_ENABLED(CONFIG_HYPERV) +#ifdef CONFIG_HYPERV_TIMER extern struct clocksource *hyperv_cs; extern void hv_init_clocksource(void); -#endif /* CONFIG_HYPERV */ -#ifdef CONFIG_HYPERV_TSCPAGE extern struct ms_hyperv_tsc_page *hv_get_tsc_page(void); static inline notrace u64
@@ -91,7 +89,7 @@ hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg) return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc); } -#else /* CONFIG_HYPERV_TSC_PAGE */ +#else /* CONFIG_HYPERV_TIMER */ static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void) { return NULL;
@@ -102,6 +100,6 @@ static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg, { return U64_MAX; } -#endif /* CONFIG_HYPERV_TSCPAGE */ +#endif /* CONFIG_HYPERV_TIMER */ #endif
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2.20.1