Commit 5/14 of sched_lock decomposition.
- Protect the cp_time tick counts with atomics instead of a global lock. There will only be one atomic per tick and this allows all processors to execute softclock concurrently. - In softclock, protect access to rusage and td_*tick data with the thread_lock(), expanding the scope of the thread lock over the whole function. - Do some creative re-arranging in hardclock() to avoid excess locking. - Protect the p_timer fields with the per-process spinlock. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=170297
@ -201,32 +201,35 @@ hardclock_cpu(int usermode)
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struct pstats *pstats;
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struct thread *td = curthread;
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struct proc *p = td->td_proc;
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int ast;
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/*
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* Run current process's virtual and profile time, as needed.
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*/
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mtx_lock_spin_flags(&sched_lock, MTX_QUIET);
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sched_tick();
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#ifdef KSE
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#if 0 /* for now do nothing */
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if (p->p_flag & P_SA) {
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/* XXXKSE What to do? Should do more. */
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}
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#endif
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#endif
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pstats = p->p_stats;
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ast = 0;
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if (usermode &&
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timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) &&
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itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0) {
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p->p_sflag |= PS_ALRMPEND;
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td->td_flags |= TDF_ASTPENDING;
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timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
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PROC_SLOCK(p);
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if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0) {
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p->p_sflag |= PS_ALRMPEND;
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ast = 1;
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}
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PROC_SUNLOCK(p);
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}
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if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value) &&
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itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0) {
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p->p_sflag |= PS_PROFPEND;
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td->td_flags |= TDF_ASTPENDING;
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if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
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PROC_SLOCK(p);
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if (itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0) {
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p->p_sflag |= PS_PROFPEND;
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ast = 1;
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}
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PROC_SUNLOCK(p);
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}
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mtx_unlock_spin_flags(&sched_lock, MTX_QUIET);
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thread_lock(td);
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sched_tick();
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if (ast)
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td->td_flags |= TDF_ASTPENDING;
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thread_unlock(td);
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#ifdef HWPMC_HOOKS
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if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
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@ -272,8 +275,8 @@ hardclock(int usermode, uintfptr_t pc)
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mtx_unlock_spin_flags(&callout_lock, MTX_QUIET);
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/*
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* swi_sched acquires sched_lock, so we don't want to call it with
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* callout_lock held; incorrect locking order.
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* swi_sched acquires the thread lock, so we don't want to call it
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* with callout_lock held; incorrect locking order.
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*/
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if (need_softclock)
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swi_sched(softclock_ih, 0);
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@ -411,6 +414,7 @@ statclock(int usermode)
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td = curthread;
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p = td->td_proc;
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thread_lock_flags(td, MTX_QUIET);
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if (usermode) {
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/*
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* Charge the time as appropriate.
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@ -420,11 +424,10 @@ statclock(int usermode)
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thread_statclock(1);
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#endif
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td->td_uticks++;
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mtx_lock_spin_flags(&time_lock, MTX_QUIET);
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if (p->p_nice > NZERO)
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cp_time[CP_NICE]++;
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atomic_add_long(&cp_time[CP_NICE], 1);
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else
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cp_time[CP_USER]++;
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atomic_add_long(&cp_time[CP_USER], 1);
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} else {
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/*
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* Came from kernel mode, so we were:
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@ -441,8 +444,7 @@ statclock(int usermode)
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if ((td->td_pflags & TDP_ITHREAD) ||
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td->td_intr_nesting_level >= 2) {
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td->td_iticks++;
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mtx_lock_spin_flags(&time_lock, MTX_QUIET);
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cp_time[CP_INTR]++;
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atomic_add_long(&cp_time[CP_INTR], 1);
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} else {
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#ifdef KSE
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if (p->p_flag & P_SA)
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@ -450,19 +452,12 @@ statclock(int usermode)
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#endif
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td->td_pticks++;
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td->td_sticks++;
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mtx_lock_spin_flags(&time_lock, MTX_QUIET);
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if (!TD_IS_IDLETHREAD(td))
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cp_time[CP_SYS]++;
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atomic_add_long(&cp_time[CP_SYS], 1);
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else
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cp_time[CP_IDLE]++;
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atomic_add_long(&cp_time[CP_IDLE], 1);
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}
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}
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mtx_unlock_spin_flags(&time_lock, MTX_QUIET);
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CTR4(KTR_SCHED, "statclock: %p(%s) prio %d stathz %d",
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td, td->td_proc->p_comm, td->td_priority, (stathz)?stathz:hz);
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mtx_lock_spin_flags(&sched_lock, MTX_QUIET);
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sched_clock(td);
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/* Update resource usage integrals and maximums. */
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MPASS(p->p_vmspace != NULL);
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@ -474,7 +469,10 @@ statclock(int usermode)
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rss = pgtok(vmspace_resident_count(vm));
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if (ru->ru_maxrss < rss)
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ru->ru_maxrss = rss;
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mtx_unlock_spin_flags(&sched_lock, MTX_QUIET);
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CTR4(KTR_SCHED, "statclock: %p(%s) prio %d stathz %d",
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td, td->td_proc->p_comm, td->td_priority, (stathz)?stathz:hz);
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sched_clock(td);
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thread_unlock(td);
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}
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void
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