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Date:   Fri, 8 May 2020 19:40:19 -0700
From:   Andi Kleen <>
To:     Ian Rogers <>
Cc:     Peter Zijlstra <>,
        Ingo Molnar <>,
        Arnaldo Carvalho de Melo <>,
        Mark Rutland <>,
        Alexander Shishkin <>,
        Jiri Olsa <>,
        Namhyung Kim <>,
        Alexei Starovoitov <>,
        Daniel Borkmann <>,
        Martin KaFai Lau <>,
        Song Liu <>, Yonghong Song <>,
        Andrii Nakryiko <>,
        John Fastabend <>,
        KP Singh <>,
        Kajol Jain <>,
        John Garry <>,
        Jin Yao <>,
        Kan Liang <>,
        Cong Wang <>,
        Kim Phillips <>,
        LKML <>,
        Networking <>, bpf <>,
        linux-perf-users <>,
        Vince Weaver <>,
        Stephane Eranian <>
Subject: Re: [RFC PATCH v3 12/14] perf metricgroup: order event groups by size

> > I'm not sure if size is that great an heuristic. The dedup algorithm should
> > work in any case even if you don't order by size, right?
> Consider two metrics:
>  - metric 1 with events {A,B}
>  - metric 2 with events {A,B,C,D}
> If the list isn't sorted then as the matching takes the first group
> with all the events, metric 1 will match {A,B} and metric 2 {A,B,C,D}.
> If the order is sorted to {A,B,C,D},{A,B} then metric 1 matches within
> the {A,B,C,D} group as does metric 2. The events in metric 1 aren't
> used and are removed.

Ok. It's better for the longer metric if they stay together.

> The dedup algorithm is very naive :-)

I guess what matters is that it gives reasonable results on the current
metrics. I assume it does?

How much deduping is happening if you run all metrics?

For toplev on my long term todo list was to compare it against
a hopefully better schedule generated by or-tools, but I never
got around to coding that up.


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