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Hi, > It _IS_ a big deal. Fetching _ONE_ hash chain cache line > is always going to be cheaper than fetching _FIVE_ to _TEN_ > page struct cache lines while walking the list. Exactly, the reason I found the pagecache hash was too small was because __find_page_nolock was one of the worst offenders when doing zero copy web serving of a large dataset. > Even if prefetch would kill all of this overhead (sorry, it won't), it > is _DUMB_ and _STUPID_ to bring those _FIVE_ to _TEN_ cache lines into > the processor just to lookup _ONE_ page. Yes you cant expect prefetch to help you when you use the data 10 instructions after you issue the prefetch. (ie walking the hash chain) Anton - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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