> On Apr 14, 2016, at 14:47, Warner Losh <i...@freebsd.org> wrote: > > Author: imp > Date: Thu Apr 14 21:47:58 2016 > New Revision: 298002 > URL: https://svnweb.freebsd.org/changeset/base/298002 > > Log: > New CAM I/O scheduler for FreeBSD. The default I/O scheduler is the same > as before. The common scheduling bits have moved from inline code in > each of the CAM periph drivers into a library that implements the > default scheduling. > > In addition, a number of rate-limiting and I/O preference options can > be enabled by adding CAM_IOSCHED_NETFLIX to your config file. A number > of extra stats are also maintained. CAM_IOSCHED_NETFLIX isn't on by > default because it uses a separate BIO_READ and BIO_WRITE queue, so > doesn't honor BIO_ORDERED between these two types of operations. We > already didn't honor it for BIO_DELETE, and we don't depend on > BIO_ORDERED between reads and writes anywhere in the system (it is > currently used with BIO_FLUSH in ZFS to make sure some writes are > complete before others start and as a poor-man's soft dependency in > one place in UFS where we won't be issuing READs until after the > operation completes). However, out of an abundance of caution, it > isn't enabled by default. > > Plus, this also brings in NCQ TRIM support for those SSDs that support > it. A black list is also provided for known rogues that use NCQ trim > as an excuse to corrupt the drive. It was difficult to separate out > into a separate commit. > > This code has run in production at Netflix for over a year now. > > Sponsored by: Netflix, Inc > Differential Revision: https://reviews.freebsd.org/D4609
I left some comments in the CR. Thanks, -Ngie _______________________________________________ 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"
