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authorVitaly Kuznetsov <vkuznets@redhat.com>2019-08-22 11:36:30 +0300
committerThomas Gleixner <tglx@linutronix.de>2019-08-23 17:59:54 +0300
commit3e2d94535adb2df15f3907e4b4c7cd8a5a4c2b5a (patch)
treeaa53940e9cf060d6afd783cdaeea0a998101722a /drivers/clocksource/hyperv_timer.c
parentbd00cd52d5be655a2f217e2ed74b91a71cb2b14f (diff)
downloadlinux-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 'drivers/clocksource/hyperv_timer.c')
-rw-r--r--drivers/clocksource/hyperv_timer.c11
1 files changed, 0 insertions, 11 deletions
diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index c322ab4d3689..2317d4e3daaf 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -213,8 +213,6 @@ 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);
struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
@@ -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)
{