linux-kernel - Re: [PATCH v3 08/10] x86/hyper-v: use hypercall for remote TLB flush

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Date:   Mon, 26 Jun 2017 18:36:46 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     Andy Lutomirski <luto@...nel.org>, devel@...uxdriverproject.org,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Jork Loeser <Jork.Loeser@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        X86 ML <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v3 08/10] x86/hyper-v: use hypercall for remote TLB flush

On Tue, May 23, 2017 at 5:36 AM, Vitaly Kuznetsov <vkuznets@...hat.com> wrote:
> Andy Lutomirski <luto@...nel.org> writes:
>
>>
>> Also, can you share the benchmark you used for these patches?
>
> I didn't do much while writing the patchset, mostly I was running the
> attached dumb trasher (32 pthreads doing mmap/munmap). On a 16 vCPU
> Hyper-V 2016 guest I get the following (just re-did the test with
> 4.12-rc1):
>
> Before the patchset:
> # time ./pthread_mmap ./randfile
>
> real    3m33.118s
> user    0m3.698s
> sys     3m16.624s
>
> After the patchset:
> # time ./pthread_mmap ./randfile
>
> real    2m19.920s
> user    0m2.662s
> sys     2m9.948s
>
> K. Y.'s guys at Microsoft did additional testing for the patchset on
> different Hyper-V deployments including Azure, they may share their
> findings too.

I ran this benchmark on my big TLB patchset, mainly to make sure I
didn't regress your test.  I seem to have sped it up by 30% or so
instead.  I need to study this a little bit to figure out why to make
sure that the reason isn't that I'm failing to do flushes I need to
do.