[Beowulf] [EXTERNAL] Re: Deskside clusters

Douglas Eadline deadline at eadline.org
Fri Sep 17 20:24:41 UTC 2021


--snip--
>
> Where I disagree with you is (3). Whether or not cache size is important
> depends on the size of the job. If your iterating through data-parallel
> loops over a large dataset that exceeds cache size, the opportunity to
> reread cached data is probably limited or nonexistent. As we often say
> here, "it depends". I'm sore someone with better low-level hardware
> knowledge will pipe in and tell me why I'm wrong (Cunningham's Law).
>

Of course it all depends. However, as core counts go up, a
fixed amount of cache must get shared. Since the high core counts
are putting pressure on main memory BW, cache gets more
important. This is why AMD is doing V-cache for new processors.
Core counts have outstripped memory BW, their solution
seems to be big caches. And, cache is only good the second time :-)


-- big snip--

-- 
Doug



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