On Wednesday, October 10, 2012 11:33:31 PM UTC-7, Mike Hommey wrote: > That being said, PGO on Linux is between 5 and 20% improvement on our > various talos tests. That's with the version of gcc we currently use, > which is 4.5. I'd expect 4.7 to do a better job even, especially if we > added lto to the equation (and since we are now building on x86-64 > machines, we wouldn't have to worry about memory usage ; link time could > be a problem, though).
Do we have detailed data? I don't know how to interpret '5-20% on various Talos tests' without context. If it's a 10% improvement on something that takes 10ms per pageload, then I don't think it matters. If it cuts 100ms from a whole pageload, then it starts to sound like it matters. I'd really like to know not only so we can make a good decision now about whether to use PGO, but also so that we can understand why we made the decision later on. PGO bugs cause crashes for our users and are miserable to debug and can feel like a waste of time to developers. I'd like to have a clear, documented understanding of either why we don't need PGO, or why PGO is worth suffering for. Dave _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
