January 22, 2007 11:25 pm
A fellow member of the Oaktable Network sent out an interesting URL. So how badly do you think a Pentium 4 overclocked to 8GHz would stall on memory loads? Can you say, “CPI?”
Posted by kevinclosson
Categories: Overclocked Pentium
Tags:
You must be logged in to post a comment.
Mobile Site | Full Site
Get a free blog at WordPress.com Theme: WordPress Mobile Edition by Alex King.
quick request for a blog entry:
I know you address it somewhat in the book, but here goes anyway:
in a NUMA multi-quad, don’t you inherently get a high CPI whenever there is a mem sync clash across quads? How does that impact on things like latches, for example? I never understood properly that section of the book and since you might know a thing or two about the subject I thought I’d ask? 😉
By Noons on January 22, 2007 at 11:52 pm
Hi Noons,
Yes, I’ll need to discuss coherency misses. It all depends on how latches are implemented. In short, using a simple test and set sort of spinlock, NUMA suffers with heavily contended latches. In the end, however, it all depends on how “lumpy” the memory is. If a remote memory write is some 100x more costly than a local memory write, then normal spinlock just don’t work–well, they don’t fail but they don’t scale 🙂
I’ll make sure to cover some of those goodies.
By kevinclosson on January 23, 2007 at 12:25 am