Hi! Sage Weil <sage@xxxxxxxxxxxx> writes: > On Tue, 12 Jan 2016, Marcel Lauhoff wrote: >> >> I wrote an article on my website with the analysis, changes to the >> source and how I ran the tests: >> >> http://irq0.org/articles/ceph/object_name_hashing > > The interesting thing to me is the error bars for linux prefix (the > right-most set of bars on the last graph). They range is significantly > wider than rjenkins + prefix (ranging from 2.1TiB to 4.0TiB (vs 2.3-3.7ish > for the others). The reason we switched away from the linux dcache hash > (it was the original choice) is because it is very weak. I suspect that > even if you look at the average + standard deviation it hides some of the > badness; looking at 99th or 99.9th percentile, or simply a plot of the osd > utilization distribution, will show that there are more low- and high- > utilization outliers. I rerun the tests and included Adler-32, CRC32, MD5 and SHA-1 (MD5 and SHA-1 truncated to 32 bit). I updated the article. In summary: Adler-32 does not work. MD5 and SHA-1 are OK. CRC32 as good as RJenkins, maybe even slightly better. ~marcel -- Marcel Lauhoff -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
