linux-kernel - Re: [PATCH 06/19] perf stat: Add 'needs_sort' argument to cpu_aggr_map_

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Message-ID: <CAM9d7ciWeQss6JkBr41gfD2FxmQprhfHsSK5ZWasJofvyVrGoA@mail.gmail.com>
Date:   Tue, 11 Oct 2022 16:32:58 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Leo Yan <leo.yan@...aro.org>, Andi Kleen <ak@...ux.intel.com>,
        Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
        James Clark <james.clark@....com>,
        Xing Zhengjun <zhengjun.xing@...ux.intel.com>
Subject: Re: [PATCH 06/19] perf stat: Add 'needs_sort' argument to cpu_aggr_map__new()

On Mon, Oct 10, 2022 at 3:53 PM Ian Rogers <irogers@...gle.com> wrote:
>
> On Sun, Oct 9, 2022 at 10:36 PM Namhyung Kim <namhyung@...nel.org> wrote:
> >
> > In case of no aggregation, it needs to keep the original (cpu) ordering
> > in the aggr_map so that it can be in sync with the cpu map.  This will
> > make the code easier to handle AGGR_NONE similar to others.
> >
>
> The CPU map is sorted and so sorting the aggr_map should be fine. If
> the data is already sorted then it is O(n) to sort. I think this is
> preferable to having additional complexity around whether the aggr_map
> is sorted.

The problem is that aggr_cpu_id__cmp() only checks socket, die and core
so it will have CPUs in the same core together - like 0, 4, 1, 5, 2, 6, 3, 7.

Thanks,
Namhyung