Hi Ted, On Mon, May 22, 2017 at 10:19:38PM -0400, Theodore Ts'o wrote: > On Mon, May 22, 2017 at 10:24:20AM -0700, Eric Biggers wrote: > > -CONFIG_LOCK_STAT=y > > -CONFIG_DEBUG_LOCKDEP=y > > Lockdep has *definitely* found bugs for us, and so I don't think we > want to turn it off. lockstat is a interesting case. It definitely > can cause performance degredations, but it also can very find > performance problems. > > I can definitely see us potentially looking for locking hotspots by > using a DAX configuration (or a /dev/ram configuration) using a > n1-highcpu-64 GCE VM. (Indeed, since Eric Whitney retired from HP, > we've lost our only "big iron" system for doing scalability testing.) > > The test appliance does currently export /proc/lock_stat via the www > interface, although we're currently not saving it in the results > tar.gz file. (That's an oversight.) > > So I have a slight preferene for leaving LOCK_STAT enabled, even if > we're not using most of the time. We're certainly not doing > performance benchmarks using this config, at any rate! > DEBUG_LOCKDEP is for debugging lockdep itself, not for turning on lockdep (that's CONFIG_PROVE_LOCKING). So I don't think it's needed. I'm fine with leaving on LOCK_STAT; I didn't know there was interest in it. Eric -- To unsubscribe from this list: send the line "unsubscribe fstests" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
