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Date: Wed, 9 Dec 2015 09:15:04 -0800
Message-ID: <CABPqkBSR+haJr-uzn3xjbP5aZ_x70FDi7ufgJi3wW7PitfqBwA@mail.gmail.com>
Subject: Re: [Questions] perf c2c: What's the current status of perf c2c?
From: Stephane Eranian <eranian@google.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Peter Zijlstra <peterz@infradead.org>, Jiri Olsa <jolsa@redhat.com>,
        Yunlong Song <yunlong.song@huawei.com>,
        Don Zickus <dzickus@redhat.com>, David Ahern <dsahern@gmail.com>,
        =?UTF-8?B?RnLDqWTDqXJpYyBXZWlzYmVja2Vy?= <fweisbec@gmail.com>,
        Joe Mario <jmario@redhat.com>, Mike Galbraith <efault@gmx.de>,
        Paul Mackerras <paulus@samba.org>, Richard Fowles <rfowles@redhat.com>,
        "acme@kernel.org >> Arnaldo Carvalho de Melo" <acme@kernel.org>,
        "mingo@redhat.com" <mingo@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jiri Olsa <jolsa@kernel.org>,
        "wangnan0@huawei.com >> Wang Nan" <wangnan0@huawei.com>,
        Richard Fowles <fowles@inreach.com>,
        Namhyung Kim <namhyung@kernel.org>
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Hi,

On Wed, Dec 9, 2015 at 8:58 AM, Andi Kleen <andi@firstfloor.org> wrote:
>> > the plan for me is to to use it some more to prove it's useful
>> > and kick it to be merged with perf at some point
>>
>> So I never really liked the c2c tool because it was so narrowly
>> focussed, it only works on NUMA thingies IIRC.
>
> It should work on all systems with an Intel Core (not Atom)
>
> However it was never clear to me if the tool was any better
> than simply sampling for
>
> mem_load_uops_l3_hit_retired.xsnp_hitm:pp    (local socket)
> mem_load_uops_l3_miss_retired.remote_hitm:pp (remote socket)
>
> which gives you instructions that reference bouncing cache lines.
>
If I recall the c2c tool is giving you more than the bouncing line. It shows you
the offset inside the line and the participating CPUs.
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