Messages in this thread | | | Subject | Re: [RFC PATCH 0/2] perf_events: add support for per-cpu per-cgroup monitoring (v3) | From | Peter Zijlstra <> | Date | Tue, 21 Sep 2010 11:38:19 +0200 |
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On Thu, 2010-09-09 at 15:05 +0200, Stephane Eranian wrote: > The cgroup to monitor is designated by passing a file descriptor opened > on a new per-cgroup file in the cgroup filesystem (perf_event.perf). The > option must be activated by setting perf_event_attr.cgroup=1 and passing > a valid file descriptor in perf_event_attr.cgroup_fd. Those are the only > two ABI extensions.
> +++ b/include/linux/perf_event.h > @@ -215,8 +215,9 @@ struct perf_event_attr { > */ > precise_ip : 2, /* skid constraint */ > mmap_data : 1, /* non-exec mmap data */ > + cgroup : 1, /* cgroup aggregation */ > > - __reserved_1 : 46; > + __reserved_1 : 45; > > union { > __u32 wakeup_events; /* wakeup every n events */ > @@ -226,6 +227,8 @@ struct perf_event_attr { > __u32 bp_type; > __u64 bp_addr; > __u64 bp_len; > + > + int cgroup_fd; > }; > > /*
I'm not sure I like this much.. so we attach to {pid,cpu}, for nodes we can use cpu_to_node(cpu), which would suggest to use cgroup_of_task(pid), except that a task can be part of multiple cgroups, so its not unique.
One thing we could do is pass this cgroup identifier in the pid field and use PERF_FLAG_CGROUP or something. Currently the syscall signature uses pid_t, but I think we can safely change that to int.
You create a special new file in the cgroup stuff, I'm not sure about that either, but its not something I feel too strongly about, why wouldn't a fd of any file or even directory of that cgroup work? Do the cgroup people have an opinion?
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