linux-kernel - Re: [PATCH v4 09/12] perf record: document parallel data streaming mode

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Message-ID: <20210408142533.GF3762101@tassilo.jf.intel.com>
Date:   Thu, 8 Apr 2021 07:25:33 -0700
From:   Andi Kleen <ak@...ux.intel.com>
To:     "Bayduraev, Alexey V" <alexey.v.bayduraev@...ux.intel.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Alexei Budankov <abudankov@...wei.com>,
        Alexander Antonov <alexander.antonov@...ux.intel.com>
Subject: Re: [PATCH v4 09/12] perf record: document parallel data streaming
 mode

> +--threads=<spec>::
> +Write collected trace data into several data files using parallel threads.
> +<spec> value can be user defined list of masks. Masks separated by colon
> +define cpus to be monitored by a thread and affinity mask of that thread
> +is separated by slash. For example user specification like the following:
> +<cpus mask 1>/<affinity mask 1>:<cpu mask 2>/<affinity mask 2> specifies

You need to be more clear on the exact syntax of a mask. Ideally
some full examples too.

> +parallel threads layout that consists of two threads with corresponding
> +assigned cpus to be monitored. <spec> value can also be a string meaning
> +predefined parallel threads layout:
> +    cpu    - create new data streaming thread for every monitored cpu
> +    core   - create new thread to monitor cpus grouped by a core
> +    socket - create new thread to monitor cpus grouped by a socket
> +    numa   - create new threed to monitor cpus grouped by a numa domain
> +Predefined layouts can be used on systems with large number of cpus in
> +order not to spawn multiple per-cpu streaming threads but still avoid LOST
> +events in data directory files. Option specified with no or empty value
> +defaults to cpu layout. Masks defined or provided by the option value are
> +filtered through the mask provided by -C option.
>  
> 
>