Messages in this thread | | | Date | Wed, 13 Mar 2024 17:00:38 -0700 | From | Andi Kleen <> | Subject | Re: [RFC PATCH v4 2/6] perf stat: Fork and launch perf record when perf stat needs to get retire latency value for a metric. |
| |
> We could use -a -C and cgroup together. I think this could be a useful use case. > There could be other improvement to the implementation in next step. But I believe
I don't know how you would improve it. A lot of the problems are fairly fundamental.
> current implementation could provide users the access to our new feature with > accurate results > and without adding too much overhead.
perf record increases the overhead a lot over a perf stat! Sampling is much more expensive than counting.
That should be at least a order of magnitude difference. Another advantage of doing it separately.
That will also make it inaccurate.
Please do a proper implementation. This one is no good.
You can likely reuse a lot of your code:
- Add a perf calibrate to run the profile step separately that generates the JSON - Add a --metrics option to perf to read the resulting JSON - Add some mechanism to read a default JSON as fallback. I guess this one could be compiled in to avoid a dependency on an installed file.
-Andi
| |