Over on the Julia discussion list there are often topics on performance or varying performance - these often turn out to be due to the BLAS libraries in use, and how they are being used. I believe that there is a project for pureJulia BLAS.
On Mon, 20 Sept 2021 at 18:41, Lux, Jim (US 7140) via Beowulf < beowulf@beowulf.org> wrote: > > > > > *From: *Beowulf <beowulf-boun...@beowulf.org> on behalf of Lawrence > Stewart <stew...@serissa.com> > *Date: *Monday, September 20, 2021 at 9:17 AM > *To: *Jim Cownie <jcow...@gmail.com> > *Cc: *Lawrence Stewart <stew...@serissa.com>, Douglas Eadline < > deadl...@eadline.org>, "beowulf@beowulf.org" <beowulf@beowulf.org> > *Subject: *Re: [Beowulf] [EXTERNAL] Re: Deskside clusters > > > > Well said. Expanding on this, caches work because of both temporal > locality and > > spatial locality. Spatial locality is addressed by having cache lines be > substantially > > larger than a byte or word. These days, 64 bytes is pretty common. Some > prefetch schemes, > > like the L1D version that fetches the VA ^ 64 clearly affect spatial > locality. Streaming > > prefetch has an expanded notion of “spatial” I suppose! > > > > What puzzles me is why compilers seem not to have evolved much notion of > cache management. It > > seems like something a smart compiler could do. Instead, it is left to > Prof. Goto and the folks > > at ATLAS and BLIS to figure out how to rewrite algorithms for efficient > cache behavior. To my > > limited knowledge, compilers don’t make much use of PREFETCH or any > non-temporal loads and stores > > either. It seems to me that once the programmer helps with RESTRICT and so > forth, then compilers could perfectly well dynamically move parts of arrays > around to maximize cache use. > > > > -L > > > > I suspect that there’s enough variability among cache implementation and > the wide variety of algorithms that might use it that writing a > smart-enough compiler is “hard” and “expensive”. > > > > Leaving it to the library authors is probably the best “bang for the > buck”. > > > > > > > _______________________________________________ > Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing > To change your subscription (digest mode or unsubscribe) visit > https://beowulf.org/cgi-bin/mailman/listinfo/beowulf >
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