Messages in this thread | | | Date | Wed, 2 Aug 2023 11:39:41 -1000 | From | Tejun Heo <> | Subject | Re: [External] Re: [PATCH] cgroup/rstat: record the cumulative per-cpu time of cgroup and its descendants |
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Hello,
On Thu, Jul 27, 2023 at 07:44:28AM -1000, Tejun Heo wrote: > Oh yeah, I do. I'm just thinking whether we also want to expose that in the > cgroupfs. We are currently not showing anything per-cpu and the output > formatting gets nasty with a huge number of CPUs, so maybe that's not going > to work out all that well. Anyways, I'll get back to you next week.
I couldn't come up with an answer. Let's go ahead with adding the field but can you please do the followings?
* Name it to something like subtree_bstat instead of cumul_bstat. The counters are all cumulative.
* Are you sure the upward propagation logic is correct? It's calculating global delta and then propagating to the per-cpu delta of the parent. Is that correct because the two delta calculations always end up the same?
* Please add a comment explaining that the field is not currently used outside of being read from bpf / drgn and what not and that we're still trying to determine how to expose that in the cgroupfs interface.
Thanks.
-- tejun
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