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| author | Warner Losh <imp@FreeBSD.org> | 2022-05-01 17:18:27 +0000 |
|---|---|---|
| committer | Warner Losh <imp@FreeBSD.org> | 2022-05-01 17:27:34 +0000 |
| commit | d592c0db8ba773c143eeea28610288f800fa651a (patch) | |
| tree | a4b701a8451dccd76721a54d77914d5e543be7b8 /sys/cam | |
| parent | b65803ba5773d5fb37fa2403105db199569a5811 (diff) | |
| download | src-d592c0db8ba773c143eeea28610288f800fa651a.tar.gz src-d592c0db8ba773c143eeea28610288f800fa651a.zip | |
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
Diffstat (limited to 'sys/cam')
| -rw-r--r-- | sys/cam/cam_iosched.c | 13 |
1 files 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, |