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From: Ali Saidi <alisaidi@amazon.com>
To: <kan.liang@linux.intel.com>
Cc: <Nick.Forrington@arm.com>, <acme@kernel.org>,
	<ak@linux.intel.com>, <alexander.shishkin@linux.intel.com>,
	<alisaidi@amazon.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>
Subject: Re: [PATCH v5 2/5] perf: Add SNOOP_PEER flag to perf mem data struct
Date: Fri, 22 Apr 2022 21:22:49 +0000	[thread overview]
Message-ID: <20220422212249.22463-1-alisaidi@amazon.com> (raw)
In-Reply-To: <c17dedde-6ba8-db9b-4827-32477f039764@linux.intel.com>


On Fri, 22 Apr 2022 21:43:28, Kan Liang wrote:
> 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
  
In this case the semantics are different. We know the line was transferred from
another peer cache, but don't know if it was clean, dirty, or if the receiving core
now has exclusive ownership of it.

Thanks,

Ali

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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Ali Saidi <alisaidi@amazon.com>
To: <kan.liang@linux.intel.com>
Cc: <Nick.Forrington@arm.com>, <acme@kernel.org>,
	<ak@linux.intel.com>, <alexander.shishkin@linux.intel.com>,
	<alisaidi@amazon.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>
Subject: Re: [PATCH v5 2/5] perf: Add SNOOP_PEER flag to perf mem data struct
Date: Fri, 22 Apr 2022 21:22:49 +0000	[thread overview]
Message-ID: <20220422212249.22463-1-alisaidi@amazon.com> (raw)
In-Reply-To: <c17dedde-6ba8-db9b-4827-32477f039764@linux.intel.com>


On Fri, 22 Apr 2022 21:43:28, Kan Liang wrote:
> 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
  
In this case the semantics are different. We know the line was transferred from
another peer cache, but don't know if it was clean, dirty, or if the receiving core
now has exclusive ownership of it.

Thanks,

Ali

  reply	other threads:[~2022-04-22 21:24 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-08 19:53 [PATCH v4 0/4] perf: arm-spe: Decode SPE source and use for perf c2c Ali Saidi
2022-04-08 19:53 ` Ali Saidi
2022-04-08 19:53 ` [PATCH v5 1/5] tools: arm64: Import cputype.h Ali Saidi
2022-04-08 19:53   ` Ali Saidi
2022-04-18 14:57   ` Leo Yan
2022-04-18 14:57     ` Leo Yan
2022-04-08 19:53 ` [PATCH v5 2/5] perf: Add SNOOP_PEER flag to perf mem data struct Ali Saidi
2022-04-08 19:53   ` Ali Saidi
2022-04-20  8:20   ` Leo Yan
2022-04-20  8:20     ` Leo Yan
2022-04-20 18:43   ` Liang, Kan
2022-04-20 18:43     ` Liang, Kan
2022-04-22 18:49     ` Ali Saidi
2022-04-22 18:49       ` Ali Saidi
2022-04-22 21:08       ` Liang, Kan
2022-04-22 21:08         ` Liang, Kan
2022-04-22 21:22         ` Ali Saidi [this message]
2022-04-22 21:22           ` Ali Saidi
2022-04-23  6:38           ` Leo Yan
2022-04-23  6:38             ` Leo Yan
2022-04-23 12:53             ` Andi Kleen
2022-04-23 12:53               ` Andi Kleen
2022-04-24 11:43               ` Leo Yan
2022-04-24 11:43                 ` Leo Yan
2022-04-25 17:01                 ` Liang, Kan
2022-04-25 17:01                   ` Liang, Kan
2022-04-27 16:19                   ` Leo Yan
2022-04-27 16:19                     ` Leo Yan
2022-04-27 19:29                     ` Liang, Kan
2022-04-27 19:29                       ` Liang, Kan
2022-04-29  9:28                       ` Leo Yan
2022-04-29  9:28                         ` Leo Yan
2022-04-08 19:53 ` [PATCH v5 3/5] perf tools: sync addition of PERF_MEM_SNOOPX_PEER Ali Saidi
2022-04-08 19:53   ` Ali Saidi
2022-04-11 10:26   ` German Gomez
2022-04-11 10:26     ` German Gomez
2022-04-11 14:35     ` German Gomez
2022-04-11 14:35       ` German Gomez
2022-04-20  8:23       ` Leo Yan
2022-04-20  8:23         ` Leo Yan
2022-04-08 19:53 ` [PATCH v5 4/5] perf arm-spe: Use SPE data source for neoverse cores Ali Saidi
2022-04-08 19:53   ` Ali Saidi
2022-04-20  8:30   ` Leo Yan
2022-04-20  8:30     ` Leo Yan
2022-04-20  8:42   ` Leo Yan
2022-04-20  8:42     ` Leo Yan
2022-04-08 19:53 ` [PATCH v5 5/5] perf mem: Support mem_lvl_num in c2c command Ali Saidi
2022-04-08 19:53   ` Ali Saidi
2022-04-11 10:04   ` German Gomez
2022-04-11 10:04     ` German Gomez
2022-04-20  8:48     ` Leo Yan
2022-04-20  8:48       ` Leo Yan
2022-04-20 16:47       ` Arnaldo Carvalho de Melo
2022-04-20 16:47         ` Arnaldo Carvalho de Melo
2022-04-20 19:02   ` Liang, Kan
2022-04-20 19:02     ` Liang, Kan

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