Peter Zijlstra <pet...@infradead.org> writes: > On Fri, Sep 23, 2016 at 05:27:22PM +0300, Alexander Shishkin wrote: >> > Afaict there's no actual need to hide the AUX buffer for this sampling >> > stuff; the user knows about all this and can simply mmap() the AUX part. >> >> Yes, you're right here. We could also re-use the AUX record, adding a >> new flag for this. It may be even better if I can work out the >> inheritance (the current code doesn't handle inheritance at the moment >> in case we decide to scrap it). > > What is the exact problem with inheritance? You can inherit PT (and > other) events just fine, and their output redirects to the original > (AUX) buffer too. > > Is the problem untangling which part of the AUX buffer belongs to which > task upon sample?
Tasks we can figure out from id samples on RECORD_AUX (assuming we're using those), but which event (if you have multiple) does a sample belong to is trickier. Cutting out samples becomes more interesting as normally RECORD_AUX don't overlap, we can keep it that way and then the samples will naturally be non-overlapping, but will all be different sizes. And there is a question of waking up the consumer often enough to copy out all the samples before the buffer overwrites itself. Let me think a bit. Regards, -- Alex
