Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Mon, 18 May 2020 21:20:51 +0200
From:   Jiri Olsa <jolsa@redhat.com>
To:     "Paul A. Clarke" <pc@us.ibm.com>
Cc:     Ian Rogers <irogers@google.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Andrii Nakryiko <andriin@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@chromium.org>,
        Kajol Jain <kjain@linux.ibm.com>,
        Andi Kleen <ak@linux.intel.com>,
        John Garry <john.garry@huawei.com>,
        Jin Yao <yao.jin@linux.intel.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        Kim Phillips <kim.phillips@amd.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Leo Yan <leo.yan@linaro.org>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, bpf@vger.kernel.org,
        Stephane Eranian <eranian@google.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: metric expressions including metrics?
Message-ID: <20200518192051.GE11620@krava>
References: <20200518191242.GA27634@oc3272150783.ibm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200518191242.GA27634@oc3272150783.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, May 18, 2020 at 02:12:42PM -0500, Paul A. Clarke wrote:
> I'm curious how hard it would be to define metrics using other metrics,
> in the metrics definition files.
> 
> Currently, to my understanding, every metric definition must be an
> expresssion based solely on arithmetic combinations of hardware events.
> 
> Some metrics are hierarchical in nature such that a higher-level metric
> can be defined as an arithmetic expression of two other metrics, e.g.
> 
> cache_miss_cycles_per_instruction =
>   data_cache_miss_cycles_per_instruction +
>   instruction_cache_miss_cycles_per_instruction
> 
> This would need to be defined something like:
> dcache_miss_cpi = "dcache_miss_cycles / instructions"
> icache_miss_cpi = "icache_miss_cycles / instructions"
> cache_miss_cpi = "(dcache_miss_cycles + icache_miss_cycles) / instructions"
> 
> Could the latter definition be simplified to:
> cache_miss_cpi = "dcache_miss_cpi + icache_miss_cpi"
> 
> With multi-level caches and NUMA hierarchies, some of these higher-level
> metrics can involve a lot of hardware events.
> 
> Given the recent activity in this area, I'm curious if this has been
> considered and already on a wish/to-do list, or found onerous.

hi,
actually we were discussing this with Ian and Stephane and I plan on
checking on that.. should be doable, I'll keep you in the loop

jirka

> 
> Regards,
> Paul Clarke
>