On Wed, Nov 03, 2010 at 03:20:59PM -0400, Owen Taylor wrote: > On Wed, 2010-11-03 at 19:58 +0100, Jakub Jelinek wrote: > > On Wed, Nov 03, 2010 at 02:48:12PM -0400, Owen Taylor wrote: > > Instead of this, which really is a big performance penalty. > > Do you have a sense of the quantification of "big" here? I know in > compiler terms, 1% is big, but we're no where close to wringing the last > 1% out of overall Fedora performance. If you create a sufficiently > complex system, there's lots of "stupid" stuff going on. And you can't > find the stupid stuff without appropriate tools. The last numbers I was pointed at for x86_64 were 4% slowdown, which really is a lot and it takes several years to achieve that improvement on the compiler side. > It seems like if it was that easy, it would have happened and we'd have > a solution in the upstream kernel... I think we had one in the upstream kernel for some time, then Linus just didn't like to see it needing too many bugfixes needed for it and nuked it. > (One thing that definitely makes things tricky is paging in debuginfo. I > think I saw a discussion somewhere that systemtap preemptively was > paging in all debuginfo for traced modules. That's tricky in systemwide Yeah, systemtap does that (and has that in kernel unwinder for userspace). Jakub -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
