linux-kernel - [PATCH RFC 0/2] x86/vdso: Add Hyper-V TSC page clocksource support

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Date:   Wed,  8 Feb 2017 18:07:42 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     x86@...nel.org, Andy Lutomirski <luto@...capital.net>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Dexuan Cui <decui@...rosoft.com>, linux-kernel@...r.kernel.org,
        devel@...uxdriverproject.org,
        virtualization@...ts.linux-foundation.org
Subject: [PATCH RFC 0/2] x86/vdso: Add Hyper-V TSC page clocksource support

Hi,

Hyper-V TSC page clocksource is suitable for vDSO, however, the protocol
defined by the hypervisor is different from VCLOCK_PVCLOCK. I implemented
the required support re-using pvclock_page VVAR. 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    0m50.218s
user    0m50.171s
sys     0m0.016s

So it seems it is worth it. What do you think?

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 | 48 ++++++++++++++++++++++++++++++++++++
 arch/x86/entry/vdso/vma.c            | 26 +++++++++++++------
 arch/x86/hyperv/hv_init.c            |  8 ++++++
 arch/x86/include/asm/clocksource.h   |  3 ++-
 arch/x86/include/asm/mshyperv.h      |  8 ++++++
 drivers/hv/Kconfig                   |  5 ++++
 6 files changed, 90 insertions(+), 8 deletions(-)

-- 
2.9.3