On 13/01/20(Mon) 21:31, Martin Pieuchot wrote:
> I'd like hardclock() to be free of SCHED_LOCK(), the diff below brings
> us one step away from that goal. Please test with your favorite
> benchmark and report any regression :o)
>
> The reason for moving the SCHED_LOCK() away from hardclock() is because
> it will allow us to re-commit the diff moving accounting out of the
> SCHED_LOCK(). In the end we shrink the SCHED_LOCK() which is generally
> a good thing(tm).
>
> `p_priority' is not very well named. It's currently a placeholder for
> three values:
>
> - the sleeping priority, corresponding to the value passed to tsleep(9)
> which will be later used by setrunnable() to place the thread on the
> appropriate runqueue.
>
> - the per-CPU runqueue priority which is used to add/remove a thread
> to/from a runqueue.
>
> - the scheduling priority, also named `p_usrpri', calculated from the
> estimated amount of CPU time used.
>
>
> The diff below splits the current `p_priority' into two fields `p_runpri'
> and `p_slppri'. The important part is the schedclock() chunk:
>
> @@ -519,8 +515,6 @@ schedclock(struct proc *p)
> SCHED_LOCK(s);
> newcpu = ESTCPULIM(p->p_estcpu + 1);
> setpriority(p, newcpu, p->p_p->ps_nice);
> - if (p->p_priority >= PUSER)
> - p->p_priority = p->p_usrpri;
> SCHED_UNLOCK(s);
>
> `p_priority' had to be updated because it was overwritten during each
> tsleep()/setrunnable() cycle. The same happened in schedcpu():
>
> schedcpu: reseting priority for zerothread(44701) 127 -> 90
> schedclock: reseting priority for zerothread(44701) 127 -> 91
>
> Getting rid of this assignment means we can then protect `p_estcpu' and
> `p_usrpri' with a custom rer-thread lock.
>
> With this division, `p_runpri' becomes part of the scheduler fields while
> `p_slppri' is obviously part of the global sleepqueue.
>
> The rest of the diff is quite straightforward, including the userland
> compatibility bits.
>
> Tests, comments and oks welcome :o)
Updated diff that changes getpriority() into a macro allowing libkvm to
build as reported by anton@.
Index: arch/sparc64/sparc64/db_interface.c
===================================================================
RCS file: /cvs/src/sys/arch/sparc64/sparc64/db_interface.c,v
retrieving revision 1.54
diff -u -p -r1.54 db_interface.c
--- arch/sparc64/sparc64/db_interface.c 7 Nov 2019 14:44:53 -0000 1.54
+++ arch/sparc64/sparc64/db_interface.c 14 Jan 2020 16:02:08 -0000
@@ -958,10 +958,10 @@ db_proc_cmd(addr, have_addr, count, modi
return;
}
db_printf("process %p:", p);
- db_printf("pid:%d vmspace:%p pmap:%p ctx:%x wchan:%p pri:%d upri:%d\n",
+ db_printf("pid:%d vmspace:%p pmap:%p ctx:%x wchan:%p rpri:%d upri:%d\n",
p->p_p->ps_pid, p->p_vmspace, p->p_vmspace->vm_map.pmap,
p->p_vmspace->vm_map.pmap->pm_ctx,
- p->p_wchan, p->p_priority, p->p_usrpri);
+ p->p_wchan, p->p_runpri, p->p_usrpri);
db_printf("maxsaddr:%p ssiz:%dpg or %llxB\n",
p->p_vmspace->vm_maxsaddr, p->p_vmspace->vm_ssize,
(unsigned long long)ptoa(p->p_vmspace->vm_ssize));
Index: dev/pci/drm/i915/intel_breadcrumbs.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/drm/i915/intel_breadcrumbs.c,v
retrieving revision 1.4
diff -u -p -r1.4 intel_breadcrumbs.c
--- dev/pci/drm/i915/intel_breadcrumbs.c 10 Jul 2019 07:56:30 -0000
1.4
+++ dev/pci/drm/i915/intel_breadcrumbs.c 14 Jan 2020 16:02:08 -0000
@@ -451,7 +451,7 @@ static bool __intel_engine_add_wait(stru
#ifdef __linux__
if (wait->tsk->prio > to_wait(parent)->tsk->prio) {
#else
- if (wait->tsk->p_priority >
to_wait(parent)->tsk->p_priority) {
+ if (wait->tsk->p_usrpri >
to_wait(parent)->tsk->p_usrpri) {
#endif
p = &parent->rb_right;
first = false;
@@ -538,7 +538,7 @@ static inline bool chain_wakeup(struct r
#else
static inline bool chain_wakeup(struct rb_node *rb, int priority)
{
- return rb && to_wait(rb)->tsk->p_priority <= priority;
+ return rb && to_wait(rb)->tsk->p_usrpri <= priority;
}
#endif
@@ -558,7 +558,7 @@ static inline int wakeup_priority(struct
if (p == b->signaler)
return INT_MIN;
else
- return p->p_priority;
+ return p->p_usrpri;
}
#endif
Index: kern/kern_fork.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_fork.c,v
retrieving revision 1.220
diff -u -p -r1.220 kern_fork.c
--- kern/kern_fork.c 6 Jan 2020 10:25:10 -0000 1.220
+++ kern/kern_fork.c 14 Jan 2020 16:02:08 -0000
@@ -312,7 +312,7 @@ fork_thread_start(struct proc *p, struct
SCHED_LOCK(s);
ci = sched_choosecpu_fork(parent, flags);
- setrunqueue(ci, p, p->p_priority);
+ setrunqueue(ci, p, p->p_usrpri);
SCHED_UNLOCK(s);
}
Index: kern/kern_proc.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_proc.c,v
retrieving revision 1.85
diff -u -p -r1.85 kern_proc.c
--- kern/kern_proc.c 12 Nov 2018 15:09:17 -0000 1.85
+++ kern/kern_proc.c 14 Jan 2020 16:02:08 -0000
@@ -476,7 +476,7 @@ proc_printit(struct proc *p, const char
(*pr)(" flags process=%b proc=%b\n",
p->p_p->ps_flags, PS_BITS, p->p_flag, P_BITS);
(*pr)(" pri=%u, usrpri=%u, nice=%d\n",
- p->p_priority, p->p_usrpri, p->p_p->ps_nice);
+ p->p_runpri, p->p_usrpri, p->p_p->ps_nice);
(*pr)(" forw=%p, list=%p,%p\n",
TAILQ_NEXT(p, p_runq), p->p_list.le_next, p->p_list.le_prev);
(*pr)(" process=%p user=%p, vmspace=%p\n",
Index: kern/kern_sched.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_sched.c,v
retrieving revision 1.62
diff -u -p -r1.62 kern_sched.c
--- kern/kern_sched.c 4 Nov 2019 18:06:03 -0000 1.62
+++ kern/kern_sched.c 14 Jan 2020 16:02:08 -0000
@@ -257,7 +257,7 @@ setrunqueue(struct cpu_info *ci, struct
p->p_cpu = ci;
p->p_stat = SRUN;
- p->p_priority = prio;
+ p->p_runpri = prio;
spc = &p->p_cpu->ci_schedstate;
spc->spc_nrun++;
@@ -277,7 +277,7 @@ void
remrunqueue(struct proc *p)
{
struct schedstate_percpu *spc;
- int queue = p->p_priority >> 2;
+ int queue = p->p_runpri >> 2;
SCHED_ASSERT_LOCKED();
spc = &p->p_cpu->ci_schedstate;
@@ -306,7 +306,7 @@ sched_chooseproc(void)
for (queue = 0; queue < SCHED_NQS; queue++) {
while ((p = TAILQ_FIRST(&spc->spc_qs[queue]))) {
remrunqueue(p);
- setrunqueue(NULL, p, p->p_priority);
+ setrunqueue(NULL, p, p->p_runpri);
if (p->p_cpu == curcpu()) {
KASSERT(p->p_flag & P_CPUPEG);
goto again;
@@ -578,7 +578,7 @@ sched_proc_to_cpu_cost(struct cpu_info *
* and the higher the priority of the proc.
*/
if (!cpuset_isset(&sched_idle_cpus, ci)) {
- cost += (p->p_priority - spc->spc_curpriority) *
+ cost += (p->p_usrpri - spc->spc_curpriority) *
sched_cost_priority;
cost += sched_cost_runnable;
}
Index: kern/kern_sig.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_sig.c,v
retrieving revision 1.241
diff -u -p -r1.241 kern_sig.c
--- kern/kern_sig.c 14 Jan 2020 08:52:18 -0000 1.241
+++ kern/kern_sig.c 14 Jan 2020 16:02:08 -0000
@@ -1130,8 +1130,8 @@ runfast:
/*
* Raise priority to at least PUSER.
*/
- if (p->p_priority > PUSER)
- p->p_priority = PUSER;
+ if (p->p_usrpri > PUSER)
+ p->p_usrpri = PUSER;
run:
setrunnable(p);
out:
@@ -1886,7 +1886,7 @@ userret(struct proc *p)
WITNESS_WARN(WARN_PANIC, NULL, "userret: returning");
- p->p_cpu->ci_schedstate.spc_curpriority = p->p_priority = p->p_usrpri;
+ p->p_cpu->ci_schedstate.spc_curpriority = p->p_usrpri;
}
int
Index: kern/kern_synch.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_synch.c,v
retrieving revision 1.157
diff -u -p -r1.157 kern_synch.c
--- kern/kern_synch.c 14 Jan 2020 08:52:18 -0000 1.157
+++ kern/kern_synch.c 14 Jan 2020 16:02:08 -0000
@@ -383,7 +383,7 @@ sleep_setup(struct sleep_state *sls, con
p->p_wchan = ident;
p->p_wmesg = wmesg;
p->p_slptime = 0;
- p->p_priority = prio & PRIMASK;
+ p->p_slppri = prio & PRIMASK;
TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_runq);
}
@@ -605,7 +605,7 @@ sys_sched_yield(struct proc *p, void *v,
*/
newprio = p->p_usrpri;
TAILQ_FOREACH(q, &p->p_p->ps_threads, p_thr_link)
- newprio = max(newprio, q->p_priority);
+ newprio = max(newprio, q->p_runpri);
setrunqueue(p->p_cpu, p, newprio);
p->p_ru.ru_nvcsw++;
mi_switch();
Index: kern/sched_bsd.c
===================================================================
RCS file: /cvs/src/sys/kern/sched_bsd.c,v
retrieving revision 1.60
diff -u -p -r1.60 sched_bsd.c
--- kern/sched_bsd.c 11 Dec 2019 07:30:09 -0000 1.60
+++ kern/sched_bsd.c 14 Jan 2020 16:02:08 -0000
@@ -254,14 +254,10 @@ schedcpu(void *arg)
newcpu = (u_int) decay_cpu(loadfac, p->p_estcpu);
setpriority(p, newcpu, p->p_p->ps_nice);
- if (p->p_priority >= PUSER) {
- if (p->p_stat == SRUN &&
- (p->p_priority / SCHED_PPQ) !=
- (p->p_usrpri / SCHED_PPQ)) {
- remrunqueue(p);
- setrunqueue(p->p_cpu, p, p->p_usrpri);
- } else
- p->p_priority = p->p_usrpri;
+ if (p->p_stat == SRUN &&
+ (p->p_runpri / SCHED_PPQ) != (p->p_usrpri / SCHED_PPQ)) {
+ remrunqueue(p);
+ setrunqueue(p->p_cpu, p, p->p_usrpri);
}
SCHED_UNLOCK(s);
}
@@ -444,6 +440,7 @@ void
setrunnable(struct proc *p)
{
struct process *pr = p->p_p;
+ u_char prio;
SCHED_ASSERT_LOCKED();
@@ -462,11 +459,15 @@ setrunnable(struct proc *p)
*/
if ((pr->ps_flags & PS_TRACED) != 0 && pr->ps_xsig != 0)
atomic_setbits_int(&p->p_siglist, sigmask(pr->ps_xsig));
+ prio = p->p_usrpri;
+ unsleep(p);
+ break;
case SSLEEP:
+ prio = p->p_slppri;
unsleep(p); /* e.g. when sending signals */
break;
}
- setrunqueue(NULL, p, p->p_priority);
+ setrunqueue(NULL, p, prio);
if (p->p_slptime > 1) {
uint32_t newcpu;
@@ -519,8 +520,6 @@ schedclock(struct proc *p)
SCHED_LOCK(s);
newcpu = ESTCPULIM(p->p_estcpu + 1);
setpriority(p, newcpu, p->p_p->ps_nice);
- if (p->p_priority >= PUSER)
- p->p_priority = p->p_usrpri;
SCHED_UNLOCK(s);
}
Index: sys/proc.h
===================================================================
RCS file: /cvs/src/sys/sys/proc.h,v
retrieving revision 1.284
diff -u -p -r1.284 proc.h
--- sys/proc.h 6 Jan 2020 10:25:10 -0000 1.284
+++ sys/proc.h 14 Jan 2020 16:03:07 -0000
@@ -341,7 +341,7 @@ struct proc {
int p_flag; /* P_* flags. */
u_char p_spare; /* unused */
char p_stat; /* [s] S* process status. */
- char p_pad1[1];
+ u_char p_runpri; /* [s] Runqueue priority */
u_char p_descfd; /* if not 255, fdesc permits this fd */
pid_t p_tid; /* Thread identifier. */
@@ -382,8 +382,8 @@ struct proc {
#define p_startcopy p_sigmask
sigset_t p_sigmask; /* Current signal mask. */
- u_char p_priority; /* [s] Process priority. */
- u_char p_usrpri; /* [s] User-prio based on p_estcpu & ps_nice. */
+ u_char p_slppri; /* [s] Sleeping priority */
+ u_char p_usrpri; /* [s] Priority based on p_estcpu & ps_nice */
u_int p_estcpu; /* [s] Time averaged val of p_cpticks */
int p_pledge_syscall; /* Cache of current syscall */
Index: sys/sysctl.h
===================================================================
RCS file: /cvs/src/sys/sys/sysctl.h,v
retrieving revision 1.199
diff -u -p -r1.199 sysctl.h
--- sys/sysctl.h 24 Dec 2019 13:13:54 -0000 1.199
+++ sys/sysctl.h 14 Jan 2020 16:14:49 -0000
@@ -561,6 +561,10 @@ struct kinfo_vmentry {
#define PR_UNLOCK(pr) /* nothing */
#endif
+#define _getcompatprio(_p) \
+ ((_p)->p_stat == SRUN ? (_p)->p_runpri : \
+ ((_p)->p_stat == SSLEEP) ? ((_p)->p_slppri) : (_p)->p_usrpri)
+
#define PTRTOINT64(_x) ((u_int64_t)(u_long)(_x))
#define FILL_KPROC(kp, copy_str, p, pr, uc, pg, paddr, \
@@ -659,7 +663,7 @@ do {
\
(kp)->p_stat = (p)->p_stat; \
(kp)->p_slptime = (p)->p_slptime; \
(kp)->p_holdcnt = 1; \
- (kp)->p_priority = (p)->p_priority; \
+ (kp)->p_priority = _getcompatprio(p); \
(kp)->p_usrpri = (p)->p_usrpri; \
if ((p)->p_wchan && (p)->p_wmesg) \
copy_str((kp)->p_wmesg, (p)->p_wmesg, \
