Some minor tunings/cleanups inspired by bde@ after previous commits:
- remove extra dynamic variable initializations; - restore (4BSD) and implement (ULE) hogticks variable setting; - make sched_rr_interval() more tolerant to options; - restore (4BSD) and implement (ULE) kern.sched.quantum sysctl, a more user-friendly wrapper for sched_slice; - tune some sysctl descriptions; - make some style fixes.
This commit is contained in:
Alexander Motin
parent
9d18043979
commit
579895df01
@ -24,7 +24,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 21, 2008
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.Dd August 10, 2012
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.Dt SCHED_ULE 4
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.Os
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.Sh NAME
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@ -59,6 +59,9 @@ The following sysctls are relevant to the operation of
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.Bl -tag -width indent
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.It Va kern.sched.name
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This read-only sysctl reports the name of the active scheduler.
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.It Va kern.sched.quantum
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This read-write sysctl reports or sets the length of the quantum (in
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micro-seconds) granted to a thread.
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.El
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.Sh SEE ALSO
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.Xr sched_4bsd 4 ,
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@ -119,9 +119,9 @@ struct td_sched {
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static struct td_sched td_sched0;
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struct mtx sched_lock;
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static int realstathz; /* stathz is sometimes 0 and run off of hz. */
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static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */
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static int sched_tdcnt; /* Total runnable threads in the system. */
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static int sched_slice = 1; /* Thread run time before rescheduling. */
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static int sched_slice = 12; /* Thread run time before rescheduling. */
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static void setup_runqs(void);
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static void schedcpu(void);
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@ -185,12 +185,32 @@ setup_runqs(void)
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runq_init(&runq);
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}
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static int
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sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
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{
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int error, new_val, period;
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period = 1000000 / realstathz;
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new_val = period * sched_slice;
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error = sysctl_handle_int(oidp, &new_val, 0, req);
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if (error != 0 || req->newptr == NULL)
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return (error);
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if (new_val <= 0)
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return (EINVAL);
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sched_slice = max(1, (new_val + period / 2) / period);
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hogticks = max(1, 2 * hz * sched_slice / realstathz);
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return (0);
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}
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SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler");
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SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0,
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"Scheduler name");
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SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
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NULL, 0, sysctl_kern_quantum, "I",
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"Length of time granted to timeshare threads in microseconds");
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SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
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"Slice size for timeshare threads");
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"Length of time granted to timeshare threads in stathz ticks");
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#ifdef SMP
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/* Enable forwarding of wakeups to all other cpus */
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static SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL,
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@ -629,21 +649,15 @@ resetpriority_thread(struct thread *td)
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static void
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sched_setup(void *dummy)
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{
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setup_runqs();
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/*
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* To avoid divide-by-zero, we set realstathz a dummy value
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* in case which sched_clock() called before sched_initticks().
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*/
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realstathz = hz;
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sched_slice = realstathz / 10; /* ~100ms */
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setup_runqs();
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/* Account for thread0. */
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sched_load_add();
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}
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/*
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* This routine determines the sched_slice after stathz and hz are setup.
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* This routine determines time constants after stathz and hz are setup.
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*/
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static void
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sched_initticks(void *dummy)
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@ -651,6 +665,7 @@ sched_initticks(void *dummy)
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realstathz = stathz ? stathz : hz;
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sched_slice = realstathz / 10; /* ~100ms */
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hogticks = max(1, 2 * hz * sched_slice / realstathz);
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}
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/* External interfaces start here */
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@ -689,7 +704,7 @@ sched_rr_interval(void)
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{
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/* Convert sched_slice from stathz to hz. */
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return (hz / (realstathz / sched_slice));
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return (max(1, (sched_slice * hz + realstathz / 2) / realstathz));
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}
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/*
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@ -724,9 +739,9 @@ sched_clock(struct thread *td)
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/*
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* Force a context switch if the current thread has used up a full
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* quantum (default quantum is 100ms).
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* time slice (default is 100ms).
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*/
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if (!TD_IS_IDLETHREAD(td) && (--ts->ts_slice <= 0)) {
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if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) {
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ts->ts_slice = sched_slice;
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td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND;
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}
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@ -201,9 +201,9 @@ static struct td_sched td_sched0;
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* preempt_thresh: Priority threshold for preemption and remote IPIs.
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*/
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static int sched_interact = SCHED_INTERACT_THRESH;
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static int realstathz;
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static int tickincr;
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static int sched_slice = 1;
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static int realstathz = 127;
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static int tickincr = 8 << SCHED_TICK_SHIFT;;
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static int sched_slice = 12;
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#ifdef PREEMPTION
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#ifdef FULL_PREEMPTION
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static int preempt_thresh = PRI_MAX_IDLE;
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@ -1363,13 +1363,6 @@ sched_setup(void *dummy)
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#else
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tdq_setup(tdq);
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#endif
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/*
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* To avoid divide-by-zero, we set realstathz a dummy value
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* in case which sched_clock() called before sched_initticks().
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*/
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realstathz = hz;
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sched_slice = (realstathz/10); /* ~100ms */
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tickincr = 1 << SCHED_TICK_SHIFT;
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/* Add thread0's load since it's running. */
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TDQ_LOCK(tdq);
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@ -1380,7 +1373,7 @@ sched_setup(void *dummy)
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}
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/*
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* This routine determines the tickincr after stathz and hz are setup.
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* This routine determines time constants after stathz and hz are setup.
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*/
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/* ARGSUSED */
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static void
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@ -1389,7 +1382,8 @@ sched_initticks(void *dummy)
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int incr;
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realstathz = stathz ? stathz : hz;
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sched_slice = (realstathz/10); /* ~100ms */
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sched_slice = realstathz / 10; /* ~100ms */
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hogticks = max(1, 2 * hz * sched_slice / realstathz);
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/*
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* tickincr is shifted out by 10 to avoid rounding errors due to
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@ -1606,8 +1600,8 @@ int
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sched_rr_interval(void)
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{
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/* Convert sched_slice to hz */
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return (hz/(realstathz/sched_slice));
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/* Convert sched_slice from stathz to hz. */
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return (max(1, (sched_slice * hz + realstathz / 2) / realstathz));
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}
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/*
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@ -2231,16 +2225,15 @@ sched_clock(struct thread *td)
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sched_interact_update(td);
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sched_priority(td);
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}
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/*
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* We used up one time slice.
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*/
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if (--ts->ts_slice > 0)
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return;
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/*
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* We're out of time, force a requeue at userret().
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* Force a context switch if the current thread has used up a full
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* time slice (default is 100ms).
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*/
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if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) {
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ts->ts_slice = sched_slice;
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td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND;
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}
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}
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/*
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@ -2795,11 +2788,31 @@ sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS)
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#endif
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static int
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sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
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{
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int error, new_val, period;
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period = 1000000 / realstathz;
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new_val = period * sched_slice;
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error = sysctl_handle_int(oidp, &new_val, 0, req);
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if (error != 0 || req->newptr == NULL)
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return (error);
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if (new_val <= 0)
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return (EINVAL);
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sched_slice = max(1, (new_val + period / 2) / period);
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hogticks = max(1, 2 * hz * sched_slice / realstathz);
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return (0);
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}
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SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler");
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SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0,
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"Scheduler name");
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SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
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NULL, 0, sysctl_kern_quantum, "I",
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"Length of time granted to timeshare threads in microseconds");
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SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
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"Slice size for timeshare threads");
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"Length of time granted to timeshare threads in stathz ticks");
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SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0,
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"Interactivity score threshold");
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SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, &preempt_thresh,
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@ -2807,9 +2820,9 @@ SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, &preempt_thresh,
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SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost,
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0,"Controls whether static kernel priorities are assigned to sleeping threads.");
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SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins,
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0,"Number of times idle will spin waiting for new work.");
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0,"Number of times idle thread will spin waiting for new work.");
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SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, &sched_idlespinthresh,
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0,"Threshold before we will permit idle spinning.");
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0,"Threshold before we will permit idle thread spinning.");
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#ifdef SMP
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SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0,
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"Number of hz ticks to keep thread affinity for");
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@ -2817,17 +2830,14 @@ SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0,
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"Enables the long-term load balancer");
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SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW,
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&balance_interval, 0,
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"Average frequency in stathz ticks to run the long-term balancer");
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"Average period in stathz ticks to run the long-term balancer");
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SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0,
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"Attempts to steal work from other cores before idling");
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SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0,
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"Minimum load on remote cpu before we'll steal");
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/* Retrieve SMP topology */
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SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING |
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CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A",
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"XML dump of detected CPU topology");
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#endif
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/* ps compat. All cpu percentages from ULE are weighted. */
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