| Date | Thu, 23 Oct 2014 14:38:55 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v5 18/20] perf: Allocate ring buffers for inherited per-task kernel events |
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On Mon, Oct 13, 2014 at 04:45:46PM +0300, Alexander Shishkin wrote: > Normally, per-task events can't be inherited parents' ring buffers to > avoid multiple events contending for the same buffer. And since buffer > allocation is typically done by the userspace consumer, there is no > practical interface to allocate new buffers for inherited counters. > > However, for kernel users we can allocate new buffers for inherited > events as soon as they are created (and also reap them on event > destruction). This pattern has a number of use cases, such as event > sample annotation and process core dump annotation. > > When a new event is inherited from a per-task kernel event that has a > ring buffer, allocate a new buffer for this event so that data from the > child task is collected and can later be retrieved for sample annotation > or core dump inclusion. This ring buffer is released when the event is > freed, for example, when the child task exits. >
This causes a pinned memory explosion, not at all nice that.
I think I see why and all, but it would be ever so good to not have to allocate so much memory.
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