On 28/06/17 22:37, Alexei Starovoitov wrote: > Increasing the limit is must have, since pruning suffered so much. > Going from 53k to 76k is pretty substantial. > What is the % increase for tests in selftests/ ? When I tried to measure the test_verifier tests, they changed hardly at all, only a couple of percent iirc. But that's with (a) only the accepted progs get measured, since rejected don't print the #insns line - and most of the tests in test_verifier are rejected; and (b) those test progs are pretty small, usually with only a couple of jumps and not much chance for pruning to occur. So it's really not a great test case for pruning effectiveness. I haven't measured the test_progs ones, because I *still* haven't gotten around to actually setting up a BPF toolchain (it doesn't help that I'm building everything on a test server that gets reimaged every night to run our nightly tests...). > I think we need to pin point exactly the reason. > Saying we just track more data is not enough. > We've tried v2 set on our load balancer and also saw ~20% increase. > I don't remember the absolute numbers. > These jumps don't make me comfortable with these extra tracking. > Can you try to roll back ptr&const and full negative/positive tracking > and see whether it gets back to what we had before? The ptr&const bit shouldn't be relevant unless your programs are actually doing that (i.e. ops on pointers other than +/-), which seems surprising. But if you really are, then it's not too hard to roll it back - just need to change how adjust_reg_min_max_vals() deals with EACCES. For a version without full negative/positive tracking, just take the first 3 patches; some of the selftests will fail but hopefully your progs will still be accepted. If not, we can try jbacik's patch (off-list response to v2). I will followup this email with a patch to apply on top of the first 3 that does that and rolls back ptr&const. > If tnum is causing it that would be reasonable trade off to make, > but if it's full neg/pos tracking that has no use today other than > (the whole thing is cleaner) I would rather drop it then. Well, the full neg/pos tracking was a result of needing to fix the bug I found with patch #1, and not wanting to confuse myself with the min/max range while doing my signed/unsigned tracking. But if we can make it work with jbacik's approach of 'remember whether our current bounds came from a signed or an unsigned compare', then we can drop or delay the full neg/pos tracking unless/until pruning is sorted out.
-Ed