On Dec 19, 2011 7:20 AM, "Dale" <rdalek1967@gmail.com> wrote:
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> Walter Dnes wrote:
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>> It's probably the sum total of the effect of all the flags. I've renamed the thread, to be more accurate. Here's how things went... * right after the install (presumably with generic i686 code) the PC could not handle streaming 1080i video from my HDHomerun TV tuner * I misinterpreted output from gcc diagnostics, and concluded that "march=-native" left several flags disabled that shouldn't be * acting on that (mis)information), I emerged system+world+kernel and found that not only could my system handle 1080i, it could handle a 1080p Youtube clip without problems, after a lot of buffering. My 5 megabit ADSL connection was the limiting factor there. It's supposed to be upgraded to 6 megabits one of these days, for some minor improvement. * I mistakenly thought that it was the additional flags in CFLAGS during the emerge system+world that boosted the video. Actually, the emerge would've done the trick. The lesson from this is that, before doing any benchmarking or heavy-duty usage, one should emerge system+world, to replace the generic code from the install CD with fully optimized code. It's easiest to so right after the initial install, so that there are as few packages to emerge as possible.
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> That is good advice too.  When I do a install, I unpack the tarball and do the normal things and get my make.conf settings done.  Since there is very little installed anyway, I do a emerge -ev world.  It usually takes only a hour or so depending on the speed of the rig.  Thing is, you then have everything compiled with your settings and not the generic ones the tarball had.  It also updates anything that needs it too.  Even before amd64 came along I did it this way.  Lots of people use Intel CPUs but I use AMD.  I don't know what the person that made the tarball uses but either way, he has to make it generic so that it will run on ANY CPU.
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> I wonder if they should mention this in the docs?  It seemed to have made a difference in your case for sure.  You went from not being able to play a video to being able to play a HD video.
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Kind of like what I always do when I switch from -march=nocona to -march=native. (Usually I use -march=nocona to ensure seamless VM migration on my XenServer-equipped boxen, but for some VMs, i.e., those requiring me to wring out every last drop of performance, I go native.)

That said, if you want to experience fully the "GCC Graphite" optimizations, you'll also want to do emerge -ev ;-)

Rgds,