Warner, On Thu, 14 Apr 2016, Warner Losh wrote:
> You add CAM_NETFLIX_IOSCHED to your kernel config to enable it. Hmmm, > looking at the diff, perhaps I should add that to LINT. > > In production, we use it for three things. First, our scheduler keeps a lot > more statistics than the default one. These statistics are useful for us > knowing when a system is saturated and needs to shed load. Second, we favor > reads over writes because our workload, as you might imagine, is a read > mostly work load. Finally, in some systems, we throttle the write throughput > to the SSDs. The SSDs we buy can do 300MB/s write while serving 400MB/s read, > but only for short periods of time (long enough to do 10-20GB of traffic). > After that, write performance drops, and read performance goes out the > window. Experiments have shown that if we limit the write speed to no more > than 30MB/s or so, then the garbage collection the drive is doing won't > adversely affect the read latency / performance. > https://people.freebsd.org/~imp/bsdcan2015/iosched-v3.pdf Thank you again for clarifications! I'd reacted because we're @work possibly can see similar (while not nearly as comparable loads, of course!) patterns. > > This code has run in production at Netflix for over a year now. > > > > Looking at this: could it be possibly targeted for MFCing? > > While this has been running in 10.x stable for the past year on our servers, > I have no plans to MFC it at this time. Great, at least it could be played with then! ;) -- Sincerely, D.Marck [DM5020, MCK-RIPE, DM3-RIPN] [ FreeBSD committer: ma...@freebsd.org ] ------------------------------------------------------------------------ *** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- ma...@rinet.ru *** ------------------------------------------------------------------------ _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
