Date: Thu, 26 Jul 2018 22:55:52 +0000 (UTC) From: Warner Losh <imp@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r336752 - head/sys/cam Message-ID: <201807262255.w6QMtqak013655@repo.freebsd.org>
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Author: imp Date: Thu Jul 26 22:55:51 2018 New Revision: 336752 URL: https://svnweb.freebsd.org/changeset/base/336752 Log: For the dynamic I/O scheduler, make the TRIM stuff also count against read bias so we do reads in preference to TRIMs. This helps a lot when many trims are delivered at once from the upper layers as they tend to delay READs due to priority inversion in the code today. The non iosched case will be fixed when the trim comibing changes needed for nvme come in later this year. Sponsored by: Netflix Modified: head/sys/cam/cam_iosched.c Modified: head/sys/cam/cam_iosched.c ============================================================================== --- head/sys/cam/cam_iosched.c Thu Jul 26 20:03:11 2018 (r336751) +++ head/sys/cam/cam_iosched.c Thu Jul 26 22:55:51 2018 (r336752) @@ -1307,7 +1307,23 @@ cam_iosched_get_trim(struct cam_iosched_softc *isc) if (!cam_iosched_has_more_trim(isc)) return NULL; - +#ifdef CAM_IOSCHED_DYNAMIC + if (do_dynamic_iosched) { + /* + * If pending read, prefer that based on current read bias + * setting. + */ + if (bioq_first(&isc->bio_queue) && isc->current_read_bias) { + isc->current_read_bias--; + /* We're not limiting TRIMS, per se, just doing reads first */ + return NULL; + } + /* + * We're going to do a trim, so reset the bias. + */ + isc->current_read_bias = isc->read_bias; + } +#endif return cam_iosched_next_trim(isc); }
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