Language is imprecise. I agree with you completely. We should pick the fastest hash that we can find and truncate it accordingly. Allen Samuels SanDisk |a Western Digital brand 2880 Junction Avenue, San Jose, CA 95134 T: +1 408 801 7030| M: +1 408 780 6416 allen.samuels@xxxxxxxxxxx > -----Original Message----- > From: Sage Weil [mailto:sweil@xxxxxxxxxx] > Sent: Friday, June 10, 2016 10:55 AM > To: Allen Samuels <Allen.Samuels@xxxxxxxxxxx> > Cc: Somnath Roy <Somnath.Roy@xxxxxxxxxxx>; Mark Nelson > <mnelson@xxxxxxxxxx>; Manavalan Krishnan > <Manavalan.Krishnan@xxxxxxxxxxx>; Ceph Development <ceph- > devel@xxxxxxxxxxxxxxx> > Subject: RE: RocksDB tuning > > On Fri, 10 Jun 2016, Allen Samuels wrote: > > Oh, and use 16-bit checksums :) > > csum_type xxhash32, 0.576609s seconds, 4655.42 MB/sec csum_type > xxhash64, 0.306633s seconds, 8754.29 MB/sec csum_type crc32c, 0.176754s > seconds, 15187 MB/sec csum_type crc32c_16, 0.172195s seconds, 15589 > MB/sec csum_type crc32c_8, 0.137655s seconds, 19500.6 MB/sec csum_type > crc16, 8.32507s seconds, 322.442 MB/sec csum_type crc16_8, 8.29444s > seconds, 323.633 MB/sec > > on my dev box. See > > https://github.com/ceph/ceph/pull/9632 > > (This is based on other stuff that's not merged; only the last few patches > there are relevant). > > I think we should drop the crc16 and just stick with low bits of crc32c, since it's > way faster... I'm pretty sure even without the intel instructions. > > sage -- 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
