On Nov 18, 2011 11:35 PM, "Pandu Poluan" <pa...@poluan.info> wrote: > > > On Nov 18, 2011 10:41 PM, "Fredric Johansson" <fredric.miscm...@gmail.com> wrote: > > > > On Wed, Nov 16, 2011 at 2:58 PM, Pandu Poluan <pa...@poluan.info> wrote: > > >
-----snip > > > > > > I've been using USE "graphite" since gcc-4.5.3-r1 appeared. Upstream says > > > that graphite is stable, feature-complete, and production-ready since 4.5.3. > > > > > > To fully taste the effect of graphite, I even went the torturous route of > > > emerging gcc + libtool + binutils (in that order) twice, followed by a > > > wholesale-rebuild of everything (emerge --emptytree), then tarballed the > > > result to my own "stage3.1" tarball to spare me the *huge* amount of time > > > required. > > > > > > I've deployed 3 systems with USE "graphite", and they *felt* snappier. > > > emerge's *felt* slower, though. (no objective tests, I know). > > > > > > I use Gentoo as a gatewall, and there I did a wholesale-rebuild one more > > > time, this time specifying CFLAGS "-march=native"... and I just couldn't be > > > happier with the resulting performance :-) > > > > > > Rgds, > > > > > > > I might be wrong but don't you need to have the gcc's options for > > graphite enabled to actually make use of the graphite framework? (You > > might be using them but you haven't mentioned it.) > > > > Yes. There are some CFLAGS incantations to add to fully utilize graphite, else the optimizations would be marginal at best. > > That said, turning on the CFLAGS flags was a *very* involved process: > > 1. By default, "graphite" is disabled. So you can't directly turn on the graphite-related CFLAGS option. You must first enable USE "graphite" and re-emerge gcc (or upgrade, if you're still using <gcc-4.5.3). This will pull in ppl and cloog-ppl. > > 2. I don't know if libtool and binutils need to be remerged, but I did it just to be safe. > > 3. Now that gcc has been compiled with graphite support, you can turn on the CFLAGS flags necessary to fully utilize graphite. WARNING: some flags recommended by upstream *might* make some programs run worse; be careful. (I won't have access to my servers so I can't tell you which ones exactly). > > 4. At this point, I want gcc itself to be optimized. So, I remerged gcc and libtool and binutils (in that order). Might be unnecessary, but I'm anal like that :-) > > 5. Finally, universe-remerge (emerge --emptytree). > > As you can see, steps 4 & 5 are optional. And they indeed took a *humongous* time to complete. But I am quite satisfied with the result. Everything felt snappier compared to older boxen that haven't been graphite-ed :-) > > Of course, YMMV. > Okay, found a forum thread discussing graphite and the proper CFLAGS: http://forums.gentoo.org/viewtopic-t-850087.html IIRC my CFLAGS looks very similar to the once @genstorm uses (scroll down to approximately 80% down the page). Now I never experienced *any* emerge failure, provided that I don't go higher than MAKEOPTS="-j3". Set it higher and several packages failed during compile. I don't know whose fault is that, but you've been warned ;-) Rgds,
