On Wed, Oct 10, 2012 at 12:04 AM, Maciej Stachowiak <m...@apple.com> wrote: > On Oct 9, 2012, at 1:50 PM, Adam Barth <aba...@webkit.org> wrote: >> That raises the question of what the cache-size to hit-rate curve >> looks like. I don't think that's something we've ever measured for >> the MemoryCache, but it would be interesting to know, for example, >> whether increasing the cache size by 4% increases the cache hit rate >> by more or less than 4%. > > My guess is that frequency of hits on given cache items approximately follows > a power law distribution, and therefore increasing cache size gives > diminishing returns. The question you raise is ceratainly an interesting one > to study to determine the optimum cache size, and to revisit when > improvements are made to cache efficiency. > > But with respect to the proposed improvement under discussion: > > If you imagine this as a curve with hit rate on the Y axis and cache size > required to achieve that hit rate on the X axis, then the potential > improvement under discussion would shift the curve down (assuming the 4% > redundancy level holds across the typical user's working set). In economic > terms, you can think of this as shifting the supply curve down (more hit rate > can be supplied at any given cost in memory), rather than movement along the > supply curve. Which is pretty good for you regardless of your demand curve > (your willingness to pay memory use for cache hit rate).
Yes, but depending on the slope of the curve, you can be introducing all this complexity for, e.g., a 1% increase in the cache hit rate. Adam _______________________________________________ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo/webkit-dev
