Thomas Gleixner <tglx@xxxxxxxxxxxxx> writes: > On Wed, 21 Aug 2019, Thomas Gleixner wrote: > >> On Wed, 21 Aug 2019, Vitaly Kuznetsov wrote: >> >> > 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 (unilizing vDSO in case of TSC page): >> > MSR based clocksource: 5664 cycles >> > TSC page clocksource: 131 cycles >> > >> > Enabling TSC page on 32bits allows us to get rid of CONFIG_HYPERV_TSCPAGE >> >> s/allows us/allows/ >> >> > as it is now not any different from CONFIG_HYPERV_TIMER. >> > >> > Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> >> > --- >> > arch/x86/include/asm/vdso/gettimeofday.h | 6 +++--- >> > drivers/clocksource/hyperv_timer.c | 11 ----------- >> > drivers/hv/Kconfig | 3 --- >> > include/clocksource/hyperv_timer.h | 6 ++---- >> > 4 files changed, 5 insertions(+), 21 deletions(-) >> >> Really nice cleanup as a side effect of adding functionality. > > That said, could you please rebase that on > > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/core > > as I just applied the TSC page patches there and this conflicts left and > right. Sure, v2 is coming! -- Vitaly
