Hi, Hyper-V TSC page clocksource is suitable for vDSO, however, the protocol defined by the hypervisor is different from VCLOCK_PVCLOCK. Implemented the required support. Simple sysbench test shows the following results: Before: # time sysbench --test=memory --max-requests=500000 run ... real 1m22.618s user 0m50.193s sys 0m32.268s After: # time sysbench --test=memory --max-requests=500000 run ... real 0m47.241s user 0m47.117s sys 0m0.008s So it seems it is worth it. As nobody seems to be strongly offended by my RFC I'm sending first non-RFC version. Patch 1 is made on top of K. Y.'s code refactoring which moved tsc page clocksource to arch/x86/hyperv/hv_init.c, this is currently present in Greg's char-misc-next tree. Changes since RFC: - Use mul_u64_u64_shr() instead of an open coded implementation [Andy Lutomirski, Thomas Gleixner] - Don't use the same pvclock_page for both VCLOCK_PVCLOCK and VCLOCK_HVCLOCK, create another one [Andy Lutomirski] - Fix issues reported by kbuild test robot. - Rename HYPERV_CLOCK -> HYPERV_TSCPAGE to avoid the ambiguity. I'm also going to try to optimize mul_u64_u64_shr() for 32bit but this can be split from this series I guess. Vitaly Kuznetsov (2): hyperv: implement hv_get_tsc_page() x86/vdso: Add VCLOCK_HVCLOCK vDSO clock read method arch/x86/entry/vdso/vclock_gettime.c | 36 +++++++++++++++++++++++++++++++++++ arch/x86/entry/vdso/vdso-layout.lds.S | 3 ++- arch/x86/entry/vdso/vdso2c.c | 3 +++ arch/x86/entry/vdso/vma.c | 7 +++++++ arch/x86/hyperv/hv_init.c | 12 ++++++++++-- arch/x86/include/asm/clocksource.h | 3 ++- arch/x86/include/asm/mshyperv.h | 8 ++++++++ arch/x86/include/asm/vdso.h | 1 + drivers/hv/Kconfig | 3 +++ 9 files changed, 72 insertions(+), 4 deletions(-) -- 2.9.3 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
