linux-kernel - Re: [PATCH v8 00/10] Hyper-V: paravirtualized remote TLB flushing and hypercall improvements

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Date:   Fri, 9 Jun 2017 09:14:47 -0700
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     devel@...uxdriverproject.org,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Jork Loeser <Jork.Loeser@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v8 00/10] Hyper-V: paravirtualized remote TLB flushing
 and hypercall improvements

On Fri,  9 Jun 2017 15:27:26 +0200
Vitaly Kuznetsov <vkuznets@...hat.com> wrote:

> Changes since v7:
> - Minor code style fixes (drop explicit casting, reformat code a bit)
>   in PATCH3 and PATCH9 [Andy Shevchenko]
> 
> 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).
> 
> Vitaly Kuznetsov (10):
>   x86/hyper-v: include hyperv/ only when CONFIG_HYPERV is set
>   x86/hyper-v: stash the max number of virtual/logical processor
>   x86/hyper-v: make hv_do_hypercall() inline
>   x86/hyper-v: fast hypercall implementation
>   hyper-v: use fast hypercall for HVCALL_SIGNAL_EVENT
>   x86/hyper-v: implement rep hypercalls
>   hyper-v: globalize vp_index
>   x86/hyper-v: use hypercall for remote TLB flush
>   x86/hyper-v: support extended CPU ranges for TLB flush hypercalls
>   tracing/hyper-v: trace hyperv_mmu_flush_tlb_others()
> 
>  MAINTAINERS                         |   1 +
>  arch/x86/Kbuild                     |   2 +-
>  arch/x86/hyperv/Makefile            |   2 +-
>  arch/x86/hyperv/hv_init.c           |  90 ++++++------
>  arch/x86/hyperv/mmu.c               | 268 ++++++++++++++++++++++++++++++++++++
>  arch/x86/include/asm/mshyperv.h     | 148 +++++++++++++++++++-
>  arch/x86/include/asm/trace/hyperv.h |  38 +++++
>  arch/x86/include/uapi/asm/hyperv.h  |  17 +++
>  arch/x86/kernel/cpu/mshyperv.c      |  13 +-
>  drivers/hv/channel_mgmt.c           |  20 +--
>  drivers/hv/connection.c             |   7 +-
>  drivers/hv/hv.c                     |   9 --
>  drivers/hv/hyperv_vmbus.h           |  11 --
>  drivers/hv/vmbus_drv.c              |  17 ---
>  drivers/pci/host/pci-hyperv.c       |  10 +-
>  include/linux/hyperv.h              |  17 +--
>  16 files changed, 539 insertions(+), 131 deletions(-)
>  create mode 100644 arch/x86/hyperv/mmu.c
>  create mode 100644 arch/x86/include/asm/trace/hyperv.h
> 

Looks good.

Reviewed-by: Stephen Hemminger <sthemmin@...rosoft.com>