On 10/12/15 8:27 PM, Wangnan (F) wrote:
Then how to avoid racing? For example, when one core disabling all events
in a map, another core is enabling all of them. This racing may causes
sereval
perf events in a map dump samples while other events not. To avoid such
racing
I think some locking must be introduced, then cost is even higher.
The reason why we introduce an atomic pointer is because each operation
should
controls a set of events, not one event, due to the per-cpu manner of
perf events.
why 'set disable' is needed ?
the example given in cover letter shows the use case where you want
to receive samples only within sys_write() syscall.
The example makes sense, but sys_write() is running on this cpu, so just
disabling it on the current one is enough.
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