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Re: [RFC PATCH v2 0/5] Additional scheduling information in tracepoints

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [RFC PATCH v2 0/5] Additional scheduling information in tracepoints
Date 2016-09-26 14:30 +0200
Message-ID <slDcK-3Ml-25@gated-at.bofh.it> (permalink)
References <skBPI-6j6-17@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Fri, Sep 23, 2016 at 12:49:30PM -0400, Julien Desfossez wrote:
> With this macro, we propose new versions of the sched_switch, sched_waking,
> sched_process_fork and sched_pi_setprio tracepoint probes that contain more
> scheduling information and get rid of the "prio" field. We also add the PI
> information to these tracepoints, so if a process is currently boosted, we show
> the name and PID of the top waiter. This allows to quickly see the blocking
> chain even if some of the trace background is missing.

Urgh.. bigger mess than ever :-(

So I thought the initial idea was to provide a 'blocked-on' tracepoint,
along with with the 'prio-changed' tracepoint, so you can reconstruct
the entire PI chain.

The only problem with that was initial state; when you start tracing (or
miss the start of a trace) its hard (impossible) to know what the
current state is.

But now you send a patch-set that just adds a metric ton of tracepoints.

This doesn't fix the current mess, it makes it worse :-(

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Thread

[RFC PATCH v2 0/5] Additional scheduling information in tracepoints Julien Desfossez <jdesfossez@efficios.com> - 2016-09-23 19:00 +0200
  [RFC PATCH v2 4/5] tracing: extend sched_pi_setprio Julien Desfossez <jdesfossez@efficios.com> - 2016-09-23 19:00 +0200
  Re: [RFC PATCH v2 0/5] Additional scheduling information in  tracepoints Peter Zijlstra <peterz@infradead.org> - 2016-09-26 14:30 +0200
    Re: [RFC PATCH v2 0/5] Additional scheduling information in  tracepoints Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2016-09-26 21:40 +0200

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