git: 6fa041d7f125 - main - Measure latency of PMC interruptions
Mateusz Guzik
mjguzik at gmail.com
Fri Sep 17 16:44:52 UTC 2021
ping?
On 9/14/21, Wojciech Macek <wma at semihalf.com> wrote:
> Hi,
>
> Thanks for comments, I'll handle all of them as well as docs.
>
> Wojtek
>
> pon., 13 wrz 2021 o 22:06 Mitchell Horne <mhorne at freebsd.org> napisał(a):
>
>> On Mon, Sep 13, 2021 at 1:11 AM Wojciech Macek <wma at freebsd.org> wrote:
>> >
>> > The branch main has been updated by wma:
>> >
>> > URL:
>> https://cgit.FreeBSD.org/src/commit/?id=6fa041d7f125db65f400af7f520a41ff78d19cd7
>> >
>> > commit 6fa041d7f125db65f400af7f520a41ff78d19cd7
>> > Author: Wojciech Macek <wma at FreeBSD.org>
>> > AuthorDate: 2021-09-13 04:08:32 +0000
>> > Commit: Wojciech Macek <wma at FreeBSD.org>
>> > CommitDate: 2021-09-13 04:08:32 +0000
>> >
>> > Measure latency of PMC interruptions
>> >
>> > Add HWPMC events to measure latency.
>> > Provide sysctl to choose the number of outstanding events which
>> > trigger HWPMC event.
>> >
>> > Obtained from: Semihalf
>> > Sponsored by: Stormshield
>> > Differential revision: https://reviews.freebsd.org/D31283
>> > ---
>> > sys/kern/kern_intr.c | 58
>> ++++++++++++++++++++++++++++++++++++++++++++++------
>> > 1 file changed, 52 insertions(+), 6 deletions(-)
>> >
>> > diff --git a/sys/kern/kern_intr.c b/sys/kern/kern_intr.c
>> > index 1660414a50ef..19401877dfbd 100644
>> > --- a/sys/kern/kern_intr.c
>> > +++ b/sys/kern/kern_intr.c
>> > @@ -30,6 +30,7 @@
>> > __FBSDID("$FreeBSD$");
>> >
>> > #include "opt_ddb.h"
>> > +#include "opt_hwpmc_hooks.h"
>> > #include "opt_kstack_usage_prof.h"
>> >
>> > #include <sys/param.h>
>> > @@ -75,6 +76,7 @@ struct intr_thread {
>> > struct thread *it_thread; /* Kernel thread. */
>> > int it_flags; /* (j) IT_* flags. */
>> > int it_need; /* Needs service. */
>> > + int it_waiting; /* Waiting in the runq. */
>> > };
>> >
>> > /* Interrupt thread flags kept in it_flags */
>> > @@ -100,13 +102,19 @@ SYSCTL_INT(_hw, OID_AUTO, intr_storm_threshold,
>> CTLFLAG_RWTUN,
>> > static int intr_epoch_batch = 1000;
>> > SYSCTL_INT(_hw, OID_AUTO, intr_epoch_batch, CTLFLAG_RWTUN,
>> &intr_epoch_batch,
>> > 0, "Maximum interrupt handler executions without re-entering
>> epoch(9)");
>> > +#ifdef HWPMC_HOOKS
>> > +static int intr_hwpmc_waiting_report_threshold = 1;
>> > +SYSCTL_INT(_hw, OID_AUTO, intr_hwpmc_waiting_report_threshold,
>> CTLFLAG_RWTUN,
>> > + &intr_hwpmc_waiting_report_threshold, 1,
>> > + "Threshold for reporting number of events in a workq");
>> > +#endif
>> > static TAILQ_HEAD(, intr_event) event_list =
>> > TAILQ_HEAD_INITIALIZER(event_list);
>> > static struct mtx event_lock;
>> > MTX_SYSINIT(intr_event_list, &event_lock, "intr event list", MTX_DEF);
>> >
>> > static void intr_event_update(struct intr_event *ie);
>> > -static int intr_event_schedule_thread(struct intr_event *ie);
>> > +static int intr_event_schedule_thread(struct intr_event *ie, struct
>> trapframe *frame);
>> > static struct intr_thread *ithread_create(const char *name);
>> > static void ithread_destroy(struct intr_thread *ithread);
>> > static void ithread_execute_handlers(struct proc *p,
>> > @@ -115,6 +123,16 @@ static void ithread_loop(void *);
>> > static void ithread_update(struct intr_thread *ithd);
>> > static void start_softintr(void *);
>> >
>> > +#ifdef HWPMC_HOOKS
>> > +#include <sys/pmckern.h>
>> > +PMC_SOFT_DEFINE( , , intr, all);
>> > +PMC_SOFT_DEFINE( , , intr, ithread);
>> > +PMC_SOFT_DEFINE( , , intr, filter);
>> > +PMC_SOFT_DEFINE( , , intr, stray);
>> > +PMC_SOFT_DEFINE( , , intr, schedule);
>> > +PMC_SOFT_DEFINE( , , intr, waiting);
>> > +#endif
>> > +
>>
>> Hi Wojciech,
>>
>> Do you plan to document these new events in the pmc.soft(3) man page?
>>
>> Cheers,
>> Mitchell
>>
>>
>> > /* Map an interrupt type to an ithread priority. */
>> > u_char
>> > intr_priority(enum intr_type flags)
>> > @@ -773,7 +791,7 @@ intr_handler_barrier(struct intr_handler *handler)
>> > }
>> > if ((handler->ih_flags & IH_CHANGED) == 0) {
>> > handler->ih_flags |= IH_CHANGED;
>> > - intr_event_schedule_thread(ie);
>> > + intr_event_schedule_thread(ie, NULL);
>> > }
>> > while ((handler->ih_flags & IH_CHANGED) != 0)
>> > msleep(handler, &ie->ie_lock, 0, "ih_barr", 0);
>> > @@ -872,7 +890,7 @@ intr_event_remove_handler(void *cookie)
>> > KASSERT((handler->ih_flags & IH_DEAD) == 0,
>> > ("duplicate handle remove"));
>> > handler->ih_flags |= IH_DEAD;
>> > - intr_event_schedule_thread(ie);
>> > + intr_event_schedule_thread(ie, NULL);
>> > while (handler->ih_flags & IH_DEAD)
>> > msleep(handler, &ie->ie_lock, 0, "iev_rmh", 0);
>> > intr_event_update(ie);
>> > @@ -944,7 +962,7 @@ intr_event_resume_handler(void *cookie)
>> > }
>> >
>> > static int
>> > -intr_event_schedule_thread(struct intr_event *ie)
>> > +intr_event_schedule_thread(struct intr_event *ie, struct trapframe
>> *frame)
>> > {
>> > struct intr_entropy entropy;
>> > struct intr_thread *it;
>> > @@ -986,11 +1004,28 @@ intr_event_schedule_thread(struct intr_event *ie)
>> > atomic_store_rel_int(&it->it_need, 1);
>> > thread_lock(td);
>> > if (TD_AWAITING_INTR(td)) {
>> > +#ifdef HWPMC_HOOKS
>> > + atomic_set_int(&it->it_waiting, 0);
>> > + if (frame != NULL)
>> > + PMC_SOFT_CALL_TF( , , intr, schedule, frame);
>> > + else
>> > + PMC_SOFT_CALL( , , intr, schedule);
>> > +#endif
>> > CTR3(KTR_INTR, "%s: schedule pid %d (%s)", __func__,
>> td->td_proc->p_pid,
>> > td->td_name);
>> > TD_CLR_IWAIT(td);
>> > sched_add(td, SRQ_INTR);
>> > } else {
>> > +#ifdef HWPMC_HOOKS
>> > + atomic_add_int(&it->it_waiting, 1);
>> > +
>> > + if (atomic_load_int(&it->it_waiting) >=
>> intr_hwpmc_waiting_report_threshold) {
>> > + if (frame != NULL)
>> > + PMC_SOFT_CALL_TF( , , intr, waiting,
>> frame);
>> > + else
>> > + PMC_SOFT_CALL( , , intr, waiting);
>> > + }
>> > +#endif
>> > CTR5(KTR_INTR, "%s: pid %d (%s): it_need %d, state %d",
>> > __func__, td->td_proc->p_pid, td->td_name,
>> it->it_need, TD_GET_STATE(td));
>> > thread_unlock(td);
>> > @@ -1083,7 +1118,7 @@ swi_sched(void *cookie, int flags)
>> > #endif
>> > } else {
>> > VM_CNT_INC(v_soft);
>> > - error = intr_event_schedule_thread(ie);
>> > + error = intr_event_schedule_thread(ie, NULL);
>> > KASSERT(error == 0, ("stray software interrupt"));
>> > }
>> > }
>> > @@ -1374,12 +1409,23 @@ intr_event_handle(struct intr_event *ie, struct
>> trapframe *frame)
>> > ret = ih->ih_filter(frame);
>> > else
>> > ret = ih->ih_filter(ih->ih_argument);
>> > +#ifdef HWPMC_HOOKS
>> > + PMC_SOFT_CALL_TF( , , intr, all, frame);
>> > +#endif
>> > KASSERT(ret == FILTER_STRAY ||
>> > ((ret & (FILTER_SCHEDULE_THREAD | FILTER_HANDLED))
>> != 0 &&
>> > (ret & ~(FILTER_SCHEDULE_THREAD | FILTER_HANDLED))
>> == 0),
>> > ("%s: incorrect return value %#x from %s", __func__,
>> ret,
>> > ih->ih_name));
>> > filter = filter || ret == FILTER_HANDLED;
>> > +#ifdef HWPMC_HOOKS
>> > + if (ret & FILTER_SCHEDULE_THREAD)
>> > + PMC_SOFT_CALL_TF( , , intr, ithread, frame);
>> > + else if (ret & FILTER_HANDLED)
>> > + PMC_SOFT_CALL_TF( , , intr, filter, frame);
>> > + else if (ret == FILTER_STRAY)
>> > + PMC_SOFT_CALL_TF( , , intr, stray, frame);
>> > +#endif
>> >
>> > /*
>> > * Wrapper handler special handling:
>> > @@ -1416,7 +1462,7 @@ intr_event_handle(struct intr_event *ie, struct
>> trapframe *frame)
>> > if (thread) {
>> > int error __unused;
>> >
>> > - error = intr_event_schedule_thread(ie);
>> > + error = intr_event_schedule_thread(ie, frame);
>> > KASSERT(error == 0, ("bad stray interrupt"));
>> > }
>> > critical_exit();
>>
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--
Mateusz Guzik <mjguzik gmail.com>
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