This is just a heads up that I've committed some changes to how the scheduler
handles realtime thread priorities. Please let me know of any issues you
encounter with nice, rtprio, or idprio. Note that as a result of these
changes, rtprio threads will no longer share priorities with interactive
timeshare threads. Instead, rtprio threads are now always more important than
non-rt threads.
--
John Baldwin
--- Begin Message ---
Author: jhb
Date: Fri Jan 14 17:06:54 2011
New Revision: 217410
URL: http://svn.freebsd.org/changeset/base/217410
Log:
Rework realtime priority support:
- Move the realtime priority range up above kernel sleep priorities and
just below interrupt thread priorities.
- Contract the interrupt and kernel sleep priority ranges a bit so that
the timesharing priority band can be increased. The new timeshare range
is now slightly larger than the old realtime + timeshare ranges.
- Change the ULE scheduler to no longer use realtime priorities for
interactive threads. Instead, the larger timeshare range is now split
into separate subranges for interactive and non-interactive ("batch")
threads. The end result is that interactive threads and non-interactive
threads still use the same priority ranges as before, but realtime
threads now have a separate, dedicated priority range.
- Do not modify the priority of non-timeshare threads in sched_sleep()
or via cv_broadcastpri(). Realtime and idle priority threads will
no longer have their priorities affected by sleeping in the kernel.
Reviewed by: jeff
Modified:
head/sys/kern/sched_4bsd.c
head/sys/kern/sched_ule.c
head/sys/kern/subr_sleepqueue.c
head/sys/sys/priority.h
Modified: head/sys/kern/sched_4bsd.c
==============================================================================
--- head/sys/kern/sched_4bsd.c Fri Jan 14 16:42:13 2011 (r217409)
+++ head/sys/kern/sched_4bsd.c Fri Jan 14 17:06:54 2011 (r217410)
@@ -908,7 +908,7 @@ sched_sleep(struct thread *td, int pri)
THREAD_LOCK_ASSERT(td, MA_OWNED);
td->td_slptick = ticks;
td->td_sched->ts_slptime = 0;
- if (pri)
+ if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
sched_prio(td, pri);
if (TD_IS_SUSPENDED(td) || pri >= PSOCK)
td->td_flags |= TDF_CANSWAP;
Modified: head/sys/kern/sched_ule.c
==============================================================================
--- head/sys/kern/sched_ule.c Fri Jan 14 16:42:13 2011 (r217409)
+++ head/sys/kern/sched_ule.c Fri Jan 14 17:06:54 2011 (r217410)
@@ -118,11 +118,17 @@ static struct td_sched td_sched0;
/*
* Priority ranges used for interactive and non-interactive timeshare
- * threads. Interactive threads use realtime priorities.
- */
-#define PRI_MIN_INTERACT PRI_MIN_REALTIME
-#define PRI_MAX_INTERACT PRI_MAX_REALTIME
-#define PRI_MIN_BATCH PRI_MIN_TIMESHARE
+ * threads. The timeshare priorities are split up into four ranges.
+ * The first range handles interactive threads. The last three ranges
+ * (NHALF, x, and NHALF) handle non-interactive threads with the outer
+ * ranges supporting nice values.
+ */
+#define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE
+ 1)
+#define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE -
SCHED_PRI_NRESV) / 2)
+
+#define PRI_MIN_INTERACT PRI_MIN_TIMESHARE
+#define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE
- 1)
+#define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE)
#define PRI_MAX_BATCH PRI_MAX_TIMESHARE
/*
@@ -1893,6 +1899,8 @@ sched_sleep(struct thread *td, int prio)
td->td_slptick = ticks;
if (TD_IS_SUSPENDED(td) || prio >= PSOCK)
td->td_flags |= TDF_CANSWAP;
+ if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
+ return;
if (static_boost == 1 && prio)
sched_prio(td, prio);
else if (static_boost && td->td_priority > static_boost)
Modified: head/sys/kern/subr_sleepqueue.c
==============================================================================
--- head/sys/kern/subr_sleepqueue.c Fri Jan 14 16:42:13 2011
(r217409)
+++ head/sys/kern/subr_sleepqueue.c Fri Jan 14 17:06:54 2011
(r217410)
@@ -745,7 +745,8 @@ sleepq_resume_thread(struct sleepqueue *
/* Adjust priority if requested. */
MPASS(pri == 0 || (pri >= PRI_MIN && pri <= PRI_MAX));
- if (pri != 0 && td->td_priority > pri)
+ if (pri != 0 && td->td_priority > pri &&
+ PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
sched_prio(td, pri);
/*
Modified: head/sys/sys/priority.h
==============================================================================
--- head/sys/sys/priority.h Fri Jan 14 16:42:13 2011 (r217409)
+++ head/sys/sys/priority.h Fri Jan 14 17:06:54 2011 (r217410)
@@ -67,10 +67,10 @@
* Priorities range from 0 to 255, but differences of less then 4 (RQ_PPQ)
* are insignificant. Ranges are as follows:
*
- * Interrupt threads: 0 - 63
- * Top half kernel threads: 64 - 127
- * Realtime user threads: 128 - 159
- * Time sharing user threads: 160 - 223
+ * Interrupt threads: 0 - 47
+ * Realtime user threads: 48 - 79
+ * Top half kernel threads: 80 - 119
+ * Time sharing user threads: 120 - 223
* Idle user threads: 224 - 255
*
* XXX If/When the specific interrupt thread and top half thread ranges
@@ -81,7 +81,7 @@
#define PRI_MAX (255) /* Lowest priority. */
#define PRI_MIN_ITHD (PRI_MIN)
-#define PRI_MAX_ITHD (PRI_MIN_KERN - 1)
+#define PRI_MAX_ITHD (PRI_MIN_REALTIME - 1)
#define PI_REALTIME (PRI_MIN_ITHD + 0)
#define PI_AV (PRI_MIN_ITHD + 4)
@@ -92,8 +92,11 @@
#define PI_SOFT (PRI_MIN_ITHD + 24)
#define PI_SWI(x) (PI_SOFT + (x) * RQ_PPQ)
-#define PRI_MIN_KERN (64)
-#define PRI_MAX_KERN (PRI_MIN_REALTIME - 1)
+#define PRI_MIN_REALTIME (48)
+#define PRI_MAX_REALTIME (PRI_MIN_KERN - 1)
+
+#define PRI_MIN_KERN (80)
+#define PRI_MAX_KERN (PRI_MIN_TIMESHARE - 1)
#define PSWP (PRI_MIN_KERN + 0)
#define PVM (PRI_MIN_KERN + 4)
@@ -106,10 +109,7 @@
#define PLOCK (PRI_MIN_KERN + 32)
#define PPAUSE (PRI_MIN_KERN + 36)
-#define PRI_MIN_REALTIME (128)
-#define PRI_MAX_REALTIME (PRI_MIN_TIMESHARE - 1)
-
-#define PRI_MIN_TIMESHARE (160)
+#define PRI_MIN_TIMESHARE (120)
#define PRI_MAX_TIMESHARE (PRI_MIN_IDLE - 1)
#define PUSER (PRI_MIN_TIMESHARE)
--- End Message ---
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