Messages in this thread | | | From | David Mosberger <> | Date | Fri, 26 Mar 2004 10:08:39 -0800 | Subject | Re: Fw: potential /dev/urandom scalability improvement |
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>>>>> On Fri, 26 Mar 2004 11:06:19 +0000, Dave Jones <davej@redhat.com> said:
Dave> On Thu, Mar 25, 2004 at 06:00:14PM -0800, Andrew Morton wrote: >> +static inline void prefetch_range(void *addr, size_t len) +{ >> +#ifdef ARCH_HAS_PREFETCH + char *cp; + char *end = addr + len; + >> + for (cp = addr; cp < end; cp += PREFETCH_STRIDE) + >> prefetch(cp); +#endif +} + #endif
Dave> I think this may be dangerous on some CPUs, if may prefetch Dave> past the end of the buffer. Ie, if PREFETCH_STRIDE was 32, and Dave> len was 65, we'd end up prefetching 65->97. As well as being Dave> wasteful to cachelines, this can crash if theres for eg Dave> nothing mapped after the next page boundary.
Huh? It only ever prefetches addresses that are _within_ the specified buffer. Of course it will prefetch entire cachelines, but I hope you're not worried about cachlines crossing page-boundaries! ;-))
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