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Date:   Fri, 22 Apr 2022 17:08:34 -0400
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Subject: Re: [PATCH v5 2/5] perf: Add SNOOP_PEER flag to perf mem data struct
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To:     Ali Saidi <alisaidi@amazon.com>
Cc:     Nick.Forrington@arm.com, acme@kernel.org,
        alexander.shishkin@linux.intel.com, andrew.kilroy@arm.com,
        benh@kernel.crashing.org, german.gomez@arm.com,
        james.clark@arm.com, john.garry@huawei.com, jolsa@kernel.org,
        kjain@linux.ibm.com, leo.yan@linaro.org, lihuafei1@huawei.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org, mark.rutland@arm.com,
        mathieu.poirier@linaro.org, mingo@redhat.com, namhyung@kernel.org,
        peterz@infradead.org, will@kernel.org,
        Andi Kleen <ak@linux.intel.com>
References: <a96681b5-5532-470e-17d1-afe4c8d195ad@linux.intel.com>
 <20220422184934.29270-1-alisaidi@amazon.com>
From:   "Liang, Kan" <kan.liang@linux.intel.com>
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On 4/22/2022 2:49 PM, Ali Saidi wrote:
> On Wed, 20 Apr 2022 18:43:28, Kan Liang wrote:
>> On 4/8/2022 3:53 PM, Ali Saidi wrote:
>>> Add a flag to the perf mem data struct to signal that a request caused a
>>> cache-to-cache transfer of a line from a peer of the requestor and
>>> wasn't sourced from a lower cache level.
>>
>> It sounds similar to the Forward state. Why can't the
>> PERF_MEM_SNOOPX_FWD be reused?
> 
> Is there a definition of SNOOPX_FWD i can refer to? Happy to use this instead if
> the semantics align between architectures.
> 

+ Andi

As my understanding, the SNOOPX_FWD means the Forward state, which is a 
non-modified (clean) cache-to-cache copy.
https://en.wikipedia.org/wiki/MESIF_protocol

Thanks,
Kan