Date: Sun, 1 May 2022 17:27:39 GMT From: Warner Losh <imp@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: d592c0db8ba7 - main - cam: add hw.cam.iosched.read_bias Message-ID: <202205011727.241HRd8m062010@gitrepo.freebsd.org>
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The branch main has been updated by imp: URL: https://cgit.FreeBSD.org/src/commit/?id=d592c0db8ba773c143eeea28610288f800fa651a commit d592c0db8ba773c143eeea28610288f800fa651a Author: Warner Losh <imp@FreeBSD.org> AuthorDate: 2022-05-01 17:18:27 +0000 Commit: Warner Losh <imp@FreeBSD.org> CommitDate: 2022-05-01 17:27:34 +0000 cam: add hw.cam.iosched.read_bias Allow a global setting for the read_bias for the dynamic io scheduler. This allows global policy to be set, in addition to the existing per-drive policy. kern.cam.iosched.read_bias is a new tunable. Sponsored by: Netflix Reviewed by: chs Differential Revision: https://reviews.freebsd.org/D34365 --- sys/cam/cam_iosched.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/sys/cam/cam_iosched.c b/sys/cam/cam_iosched.c index 21a948b69c69..c1e11419856b 100644 --- a/sys/cam/cam_iosched.c +++ b/sys/cam/cam_iosched.c @@ -139,6 +139,15 @@ SYSCTL_INT(_kern_cam_iosched, OID_AUTO, buckets, CTLFLAG_RD, &lat_buckets, LAT_BUCKETS, "Total number of latency buckets published"); +/* + * Read bias: how many reads do we favor before scheduling a write + * when we have a choice. + */ +static int default_read_bias = 0; +SYSCTL_INT(_kern_cam_iosched, OID_AUTO, read_bias, CTLFLAG_RWTUN, + &default_read_bias, 0, + "Default read bias for new devices."); + struct iop_stats; struct cam_iosched_softc; @@ -1149,7 +1158,7 @@ cam_iosched_init(struct cam_iosched_softc **iscp, struct cam_periph *periph) #ifdef CAM_IOSCHED_DYNAMIC if (do_dynamic_iosched) { bioq_init(&(*iscp)->write_queue); - (*iscp)->read_bias = 0; + (*iscp)->read_bias = default_read_bias; (*iscp)->current_read_bias = 0; (*iscp)->quanta = min(hz, 200); cam_iosched_iop_stats_init(*iscp, &(*iscp)->read_stats); @@ -1234,7 +1243,7 @@ void cam_iosched_sysctl_init(struct cam_iosched_softc *isc, SYSCTL_ADD_INT(ctx, n, OID_AUTO, "read_bias", CTLFLAG_RW, - &isc->read_bias, 0, + &isc->read_bias, default_read_bias, "How biased towards read should we be independent of limits"); SYSCTL_ADD_PROC(ctx, n,
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