Gareth Hughes wrote:
> In general, this is true. However:
> 1) All buffers (malloc()'d and DMA) are nicely aligned to at least a
> cacheline boundary.
malloc() will not always be allocated contiguous physical pages, so
there is the "colouring" problem ... we might get several pages that
are competing for cache. The application itself will use memory for
processing vertex data, etc.; perhaps that's enough to explain the
difference? It's quite a small percentage difference, but it is
consistent.
I'm not at all sure of the cause, really, but the behaviour is real
enough ... I see it myself. Not really important enough to waste any
more time on, though :)
> 2) DMA buffers reside in uncached AGP memory. Hence, caching plays no
> part in the timing of the app.
Here I'm not an expert, indeed quite the opposite, so no argument.
> -- Gareth
--
/* Bill Crawford, Unix Systems Developer, Ebone (formerly GTS Netcom) */
#include <stddiscl>
const char *addresses[] = {
"[EMAIL PROTECTED]", "[EMAIL PROTECTED]", // work
"[EMAIL PROTECTED]", "[EMAIL PROTECTED]" // home
};
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