Re: [PATCH] perf_events: add sampling period randomization support(v2)

From: Ingo Molnar
Date: Thu Mar 04 2010 - 12:18:05 EST

* eranian@xxxxxxxxxx <eranian@xxxxxxxxxx> wrote:

> This patch adds support for randomizing the sampling period. Randomization
> is very useful to mitigate the bias that exists with sampling. The random
> number generator does not need to be sophisticated. This patch uses the
> builtin random32() generator.

> + if (width > 63 || attr->freq)
> + return -EINVAL;

Why not for freq counters? Those are semi-randomized already, but it might
make sense to make them 'more' randomized in special circumstances. That would
also allow us to enable the randomization in perf top and perf record, by

Without that we'd have no immediate usecase and no way to ensure that this
code works as intended.


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