> > Linux on IA64 currently supports "granules" of 16MB and 64MB. > This is the page size used for the kernel identity-mapped > regions. Everything mapped by a page must actually exist (to > avoid MCAs when prefetching into a hole) and must have the same > attributes (to avoid attribute aliasing), so we assume that > physical memory comes in granule-sized chunks. > > DIG64 2.1 says nothing about the granularity of physical memory, > but it seems that for all existing IA64 machines, memory comes in > chunks of at least 64MB. But there's an HP machine in the pipe > that may support only 4MB granularity. > > I'm not keen on reducing the granule size to 4MB, because I'm > afraid the extra TLB misses will be a noticeable performance > problem. Does anybody have any quantitative data on the effect > of granule size on performance? Certainly nothing conclusive, but .... About 6 months ago, I ran the AIM7 benchmark with 16MB & 64MB granules. No measurable difference. The runs were indistinguishable. However, with other benchmarks (or 4MB granules), YMMV. > Or any strong opinions on what > granule sizes we should support? > > Bjorn > > _______________________________________________ > Linux-IA64 mailing list > Linux-IA64@linuxia64.org > http://lists.linuxia64.org/lists/listinfo/linux-ia64 > -- Thanks Jack Steiner (651-683-5302) (vnet 233-5302) steiner@sgi.comReceived on Wed Aug 28 12:55:23 2002
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