stackcollapse-perf.pl should be more memory-efficient

[JasonGross]

I'm concerned stackcollapse-perf.pl is going to blow through my available RAM; is there any way for it to be more streaming?

My perf.data file is almost 9GB, the output of perf script is 158GB, so maybe the answer is just that I have to use smaller runs. But it would be nice to be able to get a flamegraph out of this.

Edit: It was mem-killed a couple minutes after making this issue.

[randomstuff]

You can probably sample from your perf script output by only selecting 1/100000 data points and you should be fine.

[randomstuff]

Actually, stackcollapse-perf would have to be modified to implement a non-collapsing/streaming mode in order to do that.

[randomstuff]

See #286