Date: Thu, 14 Dec 2017 21:49:32 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Teng Qin <qinteng@fb.com>
Cc: mingo@redhat.com, ast@fb.com, bgregg@netflix.com, daniel@iogearbox.net,
        yhs@fb.com, linux-kernel@vger.kernel.org, Kernel-team@fb.com
Subject: Re: [PATCH tip 0/3] Improvements of scheduler related Tracepoints
Message-ID: <20171214204932.GH3326@worktop>
References: <20171214202044.1629279-1-qinteng@fb.com>
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On Thu, Dec 14, 2017 at 12:20:41PM -0800, Teng Qin wrote:
> This set of commits attempts to improve three scheduler related
> Tracepoints: sched_switch, sched_process_fork, sched_process_exit.
> 
> Firstly, these commit add additional flag values, namely preempt,
> clone_flags and group_dead to these Tracepoints, to make information
> exposed via the Tracepoints more useful and complete.
> 
> Secondly, these commits exposes task_struct pointers in these
> Tracepoints. The task_struct pointers are arguments of the Tracepoints
> and currently only used to compute struct field values. But for BPF
> programs attached to these Tracepoints, we may want to read additional
> task information via the task_struct pointers. This is currently either
> impossible, or we have to make assumption of whether the Tracepoint is
> running from previous / parent or next / child, and use current pointer
> instead. Exposing the task_struct pointers explicitly makes such use
> case easier and more reliable.
> 

NAK