Re: [PATCH] perf record: Add snapshot mode support for perf's regular events

From: Wangnan (F)
Date: Wed Dec 02 2015 - 03:27:13 EST


Hi Peter,

On 2015/11/25 17:27, Peter Zijlstra wrote:
On Tue, Nov 24, 2015 at 10:00:31PM +0800, Yunlong Song wrote:
In our patch, we create and maintain a user space ring buffer to store
perf's tracing info, instead of directly writing to perf.data file as
before. In snapshot mode, only a SIGUSR2 signal can trigger perf to dump
the tracing info currently stored in the user space ring buffer to
perf.data file.
I would very much like to first fix the perf overwrite mode: see
lkml.kernel.org/r/20151023151205.GW11639@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I have an idea on this problem that, is it possible to
put the size of an event at the end of it when we working
on overwrite mode? So we can backtrack every events without
too much change to ring buffer?

Thank you.

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