On Monday 03 December 2007 19:45, Ingo Molnar wrote: > * Nick Piggin <[EMAIL PROTECTED]> wrote: > > On Friday 30 November 2007 21:08, Ingo Molnar wrote: > > > * Nick Piggin <[EMAIL PROTECTED]> wrote: > > > > Haven't we been asking JVMs to use futexes or posix locking for years > > > > and years now? [...] > > > > > > i'm curious, with what JVM was it tested and where's the source so i > > > can fix their locking for them? Can the problem be reproduced with: > > > > Sure, but why shouldn't the compat behaviour be the default, and the > > sysctl go away? > > > > It makes older JVMs work better, it is slightly closer to the old > > behaviour, and it is arguably a less surprising result. > > as far as desktop apps such as firefox goes, the exact opposite is true. > We had two choices basically: either a "more agressive" yield than > before or a "less agressive" yield. Desktop apps were reported to hurt > from a "more agressive" yield (firefox for example gets some pretty bad > delays), so we defaulted to the less agressive method. (and we defaulted > to that in v2.6.23 already)
Yeah, I doubt the 2.6.23 scheduler will be usable for distros though... > Really, in this sense volanomark is another > test like dbench - we care about it but not unconditionally and in this > case it's a really silly API use that is at the center of the problem. Sure, but do you whether _real_ java server applications are OK? Is it possible to reduce the aggressiveness of yield to a mid-way? Are the firefox tests also like dbench (ie. were they done with make -j huge or some other insane scheduler loads) > Talking about the default alone will not bring us forward, but we can > certainly add helpers to identify SCHED_OTHER::yield tasks - a once per > bootup warning perhaps? I don't care about keeping the behaviour for future apps. But for older code out there, it is very important to still work well. I was just talking about the default because I didn't know the reason for the way it was set -- now that I do, we should talk about trying to improve the actual code so we don't need 2 defaults. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
