Re: [PATCH v9 00/13] Don't compute events that won't be used in a metric.

Ian Rogers
2021-09-29T16:11:00Z

On Wed, Sep 29, 2021 at 8:16 AM John Garry <john.garry@huawei.com> wrote:
>
> On 23/09/2021 08:46, Ian Rogers wrote:
> > For a metric like:
> > EVENT1 if #smt_on else EVENT2
> >
> > currently EVENT1 and EVENT2 will be measured and then when the metric
> > is reported EVENT1 or EVENT2 will be printed depending on the value
> > from smt_on() during the expr parsing. Computing both events is
> > unnecessary and can lead to multiplexing as discussed in this thread:
> > https://lore.kernel.org/lkml/20201110100346.2527031-1-irogers@google.com/
> >
> > This change modifies expression parsing so that constants are
> > considered when building the set of ids (events) and only events not
> > contributing to a constant value are measured.
>
> Based on some testing on my arm64 platform, no regression seen, so:
>
> Tested-by: John Garry <john.garry@huawei.com>

Awesome, much thanks Jiri, John, Andi for the reviews and testing!

Ian