Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
In-Reply-To: <874lq7ra4n.fsf@vitty.brq.redhat.com>
References: <20170802160921.21791-1-vkuznets@redhat.com> <CANRm+Cz7SgUJ3o2O=uDn+un4JYiqQ-aANhf4tNNArfbv6a_uOQ@mail.gmail.com>
 <87d14vrcou.fsf@vitty.brq.redhat.com> <CANRm+Cz+0kAFjpGudnoXsPnWzuM2368KDBxivV4Xi-nPwt=dXw@mail.gmail.com>
 <874lq7ra4n.fsf@vitty.brq.redhat.com>
From:   Wanpeng Li <kernellwp@gmail.com>
Date:   Mon, 6 Nov 2017 19:07:28 +0800
Message-ID: <CANRm+CwmfmKVD=VFaFb3Z9aiBD_CT=VeGbxwrcZzSdXdTfsR2Q@mail.gmail.com>
Subject: Re: [PATCH v10 0/9] Hyper-V: paravirtualized remote TLB flushing and
 hypercall improvements
To:     Vitaly Kuznetsov <vkuznets@redhat.com>
Cc:     "the arch/x86 maintainers" <x86@kernel.org>,
        devel@linuxdriverproject.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Jork Loeser <Jork.Loeser@microsoft.com>,
        Simon Xiao <sixiao@microsoft.com>,
        Andy Lutomirski <luto@kernel.org>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Paolo Bonzini <pbonzini@redhat.com>, kvm <kvm@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

2017-11-06 18:10 GMT+08:00 Vitaly Kuznetsov <vkuznets@redhat.com>:
> Wanpeng Li <kernellwp@gmail.com> writes:
>
>> 2017-11-06 17:14 GMT+08:00 Vitaly Kuznetsov <vkuznets@redhat.com>:
>>> Wanpeng Li <kernellwp@gmail.com> writes:
>>>
>>>> 2017-08-03 0:09 GMT+08:00 Vitaly Kuznetsov <vkuznets@redhat.com>:
>>>>> Changes since v9:
>>>>> - Rebase to 4.13-rc3.
>>>>> - Drop PATCH1 as it was already taken by Greg to char-misc tree. There're no
>>>>>   functional dependencies on this patch so the series can go through a different tree
>>>>>   (and it actually belongs to x86 if I got Ingo's comment right).
>>>>> - Add in missing void return type in PATCH1 [Colin King, Ingo Molnar, Greg KH]
>>>>> - A few minor fixes in what is now PATCH7: add pr_fmt, tiny style fix in
>>>>>   hyperv_flush_tlb_others() [Andy Shevchenko]
>>>>> - Fix "error: implicit declaration of function 'virt_to_phys'" in PATCH2
>>>>>   reported by kbuild test robot (#include <asm/io.h>)
>>>>> - Add Steven's 'Reviewed-by:' to PATCH9.
>>>>>
>>>>> Original description:
>>>>>
>>>>> Hyper-V supports hypercalls for doing local and remote TLB flushing and
>>>>> gives its guests hints when using hypercall is preferred. While doing
>>>>> hypercalls for local TLB flushes is probably not practical (and is not
>>>>> being suggested by modern Hyper-V versions) remote TLB flush with a
>>>>> hypercall brings significant improvement.
>>>>>
>>>>> To test the series I wrote a special 'TLB trasher': on a 16 vCPU guest I
>>>>> was creating 32 threads which were doing 100000 mmap/munmaps each on some
>>>>> big file. Here are the results:
>>>>>
>>>>> Before:
>>>>> # time ./pthread_mmap ./randfile
>>>>> real    3m33.118s
>>>>> user    0m3.698s
>>>>> sys     3m16.624s
>>>>>
>>>>> After:
>>>>> # time ./pthread_mmap ./randfile
>>>>> real    2m19.920s
>>>>> user    0m2.662s
>>>>> sys     2m9.948s
>>>>>
>>>>> This series brings a number of small improvements along the way: fast
>>>>> hypercall implementation and using it for event signaling, rep hypercalls
>>>>> implementation, hyperv tracing subsystem (which only traces the newly added
>>>>> remote TLB flush for now).
>>>>>
>>>>
>>>> Hi Vitaly,
>>>>
>>>> Could you attach your benchmark? I'm interested in to try the
>>>> implementation in paravirt kvm.
>>>>
>>>
>>> Oh, this would be cool) I briefly discussed the idea with Radim (one of
>>> KVM maintainers) during the last KVM Forum and he wasn't opposed to the
>>> idea. Need to talk to Paolo too. Good thing is that we have everything
>>
>> I talk with Paolo today and he points this feature to me, so I believe
>> he likes it. :) In addition,
>> https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs
>> I search Hypervisor Top Level Functional Specification v5.0b.pdf
>> document but didn't find a section introduce the Hyper-V:
>> paravirtualized remote TLB flushing and hypercall stuff, could you
>> point out?
>>
>
> It's there, search for
> HvFlushVirtualAddressSpace/HvFlushVirtualAddressSpaceEx and
> HvFlushVirtualAddressList/HvFlushVirtualAddressListEx.

Got it, thanks.

Regards,
Wanpeng Li

From 1583311095225729641@xxx Mon Nov 06 10:12:06 +0000 2017
X-GM-THRID: 1574636603958149385
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread