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robmoss
Retired Dev
Joined: 27 May 2003
Posts: 2634
Location: Jesus College, Oxford
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 Posted: Tue Jul 15, 2003 3:40 pm Post subject: CFLAGS: -mmmx -m3dnow -msse et al |
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I'm having a bit of a problem with the above CFLAGS. The "flags" line of cat /proc/cpuinfo gives me:
| Code: | | flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow |
on an Athlon XP 1600+. Now, it says there that I have support for:
SSE
MMX / MMX2
3DNow! / 3DNow!2
So, my question is, how do I make sure that GCC is using MMX2 and 3DNow!2 support, as well as just plain old MMX and 3DNow! support? I don't know if adding the CFLAGS:
| Code: | | -mmmxext -m3dnowext |
would make any difference at all. This is primarily to make sure that things like video encoding take as little time as possible! |
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()
l33t
Joined: 25 Nov 2002
Posts: 610
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| Posted: Tue Jul 15, 2003 3:50 pm Post subject: |
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| -march=athlon-xp should turn on sensible optimizations shouldn't it? |
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jkcunningham
l33t
Joined: 28 Apr 2003
Posts: 649
Location: 47.49N 121.79W
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| Posted: Wed Jul 16, 2003 7:52 am Post subject: Re: CFLAGS: -mmmx -m3dnow -msse et al |
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| robmoss2k wrote: | I'm having a bit of a problem with the above CFLAGS. The "flags" line of cat /proc/cpuinfo gives me:
| Code: | | flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow |
on an Athlon XP 1600+. Now, it says there that I have support for:
SSE
MMX / MMX2
3DNow! / 3DNow!2
So, my question is, how do I make sure that GCC is using MMX2 and 3DNow!2 support, as well as just plain old MMX and 3DNow! support? I don't know if adding the CFLAGS:
| Code: | | -mmmxext -m3dnowext |
would make any difference at all. This is primarily to make sure that things like video encoding take as little time as possible! |
Just because cpuinfo shows the flags doesn't mean that your hardware, or gcc for that matter supports them. Try running the gcccpuopt script and see what it says. There's a link to it on this page:
http://home.comcast.net/~jcunningham63/linux/GCC_Optimization.html
-Jeff |
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