Re: No last core parallel slowdown on OS X

2009-04-22 Thread Dave Bayer
My first post was comparing almost identical machines: Different Q6600 steppings (the earlier chip makes a good space heater!) on different motherboards, same memory, both stock speeds. In a few weeks when the semester ends, I'll be able to try Linux -vs- BSD -vs- OS X on identical

Re: No last core parallel slowdown on OS X

2009-04-21 Thread Simon Marlow
2009/4/20 Dave Bayer ba...@cpw.math.columbia.edu: I ran some longer trials, and noticed a further pattern I wish I could explain: I'm comparing the enumeration of the roughly 69 billion atomic lattices on six atoms, on my four core, 2.4 GHz Q6600 box running OS X, against an eight core, 2 x

Re: No last core parallel slowdown on OS X

2009-04-21 Thread Simon Marlow
2009/4/21 Don Stewart d...@galois.com: Little advice and tidbits are creeping out of Simon's head. Is it time for a parallel performance wiki, where every question that becomes an FAQ gets documented live?    http://haskell.org/haskellwiki/Performance/Parallel Maybe put details on the

Re: No last core parallel slowdown on OS X

2009-04-21 Thread Don Stewart
marlowsd: 2009/4/20 Dave Bayer ba...@cpw.math.columbia.edu: I ran some longer trials, and noticed a further pattern I wish I could explain: I'm comparing the enumeration of the roughly 69 billion atomic lattices on six atoms, on my four core, 2.4 GHz Q6600 box running OS X, against an

Re: No last core parallel slowdown on OS X

2009-04-21 Thread Tyson Whitehead
On April 21, 2009 04:39:40 Simon Marlow wrote: These ratios match up like physical constants, or at least invariants of my Haskell implementation. However, the user time is constant on OS X, so these ratios reflect the actual parallel speedup on OS X. The user time climbs steadily on

Re: No last core parallel slowdown on OS X

2009-04-20 Thread Simon Marlow
Manuel M T Chakravarty wrote: Dave Bayer: In that paper, they routinely benchmark N-1 cores on an N core Linux box, because of a noticeable falloff using the last core, which can do more harm than good. I had confirmed this on my four core Linux box, but was puzzled that my two core MacBook

Re: No last core parallel slowdown on OS X

2009-04-20 Thread Dave Bayer
On Apr 19, 2009, at 9:59 PM, Tyson Whitehead wrote: This leave me wondering how do the absolute numbers compare? Could the extra overhead due to the various 32bit issues be giving more room for better threading performance? What do you get if you use 32bit GHC with Linux? Oddly

Re: No last core parallel slowdown on OS X

2009-04-20 Thread Dave Bayer
[Sorry if this turns out to be a dup, it appears that my first send got lost, while my followup message went through.] I ran some longer trials, and noticed a further pattern I wish I could explain: I'm comparing the enumeration of the roughly 69 billion atomic lattices on six atoms, on

Re: No last core parallel slowdown on OS X

2009-04-19 Thread Manuel M T Chakravarty
Dave Bayer: In that paper, they routinely benchmark N-1 cores on an N core Linux box, because of a noticeable falloff using the last core, which can do more harm than good. I had confirmed this on my four core Linux box, but was puzzled that my two core MacBook showed no such falloff.

Re: No last core parallel slowdown on OS X

2009-04-19 Thread Tyson Whitehead
On April 18, 2009 16:46:44 Daniel Peebles wrote: That looks great! I wonder what about Mac OS leads to such good performance... Now if only we could get a nice x86_64-producing GHC for Mac OS too, I could use all my RAM and the extra registers my Mac Pro gives me :) I was a bit surprised

Re: No last core parallel slowdown on OS X

2009-04-18 Thread Daniel Peebles
That looks great! I wonder what about Mac OS leads to such good performance... Now if only we could get a nice x86_64-producing GHC for Mac OS too, I could use all my RAM and the extra registers my Mac Pro gives me :) On Sat, Apr 18, 2009 at 2:39 PM, Dave Bayer ba...@cpw.math.columbia.edu wrote:

Re: No last core parallel slowdown on OS X

2009-04-18 Thread Dave Bayer
Yikes! You're right. I never noticed, but I never had an 8 GB Mac before. I looked at ./configure for the GHC 6.10.2 source, and realized there was already something there. I tried ./configure --build=x86_64-apple-darwin and it didn't work. However, it did give me something to Google,

Re: No last core parallel slowdown on OS X

2009-04-18 Thread Austin Seipp
Excerpts from Dave Bayer's message of Sat Apr 18 19:05:34 -0500 2009: Yikes! You're right. I never noticed, but I never had an 8 GB Mac before. I looked at ./configure for the GHC 6.10.2 source, and realized there was already something there. I tried ./configure