Re: [PATCH v5 00/15] jevents/pmu-events improvements

John Garry
2023-01-27T13:21:41Z

On 26/01/2023 23:36, Ian Rogers wrote:

Hi Ian,

At a glance, none of this series has your Signed-off-by tag..

Thanks,
John

> Add an optimization to jevents using the metric code, rewrite metrics
> in terms of each other in order to minimize size and improve
> readability. For example, on Power8
> other_stall_cpi is rewritten from:
> "PM_CMPLU_STALL / PM_RUN_INST_CMPL - PM_CMPLU_STALL_BRU_CRU / PM_RUN_INST_CMPL - PM_CMPLU_STALL_FXU / PM_RUN_INST_CMPL - PM_CMPLU_STALL_VSU / PM_RUN_INST_CMPL - PM_CMPLU_STALL_LSU / PM_RUN_INST_CMPL - PM_CMPLU_STALL_NTCG_FLUSH / PM_RUN_INST_CMPL - PM_CMPLU_STALL_NO_NTF / PM_RUN_INST_CMPL"
> to:
> "stall_cpi - bru_cru_stall_cpi - fxu_stall_cpi - vsu_stall_cpi - lsu_stall_cpi - ntcg_flush_cpi - no_ntf_stall_cpi"
> Which more closely matches the definition on Power9.
>
> A limitation of the substitutions are that they depend on strict
> equality and the shape of the tree. This means that for "a + b + c"
> then a substitution of "a + b" will succeed while "b + c" will fail
> (the LHS for "+ c" is "a + b" not just "b").
>
> Separate out the events and metrics in the pmu-events tables saving
> 14.8% in the table size while making it that metrics no longer need to
> iterate over all events and vice versa. These changes remove evsel's
> direct metric support as the pmu_event no longer has a metric to
> populate it. This is a minor issue as the code wasn't working
> properly, metrics for this are rare and can still be properly ran
> using '-M'.
>
> Add an ability to just build certain models into the jevents generated
> pmu-metrics.c code. This functionality is appropriate for operating
> systems like ChromeOS, that aim to minimize binary size and know all
> the target CPU models.