svn commit: r357004 - in head/sys: kern sys
Hans Petter Selasky
hps at selasky.org
Fri Jan 24 09:25:05 UTC 2020
On 2020-01-23 09:36, Hans Petter Selasky wrote:
> On 2020-01-23 02:24, Gleb Smirnoff wrote:
>> Author: glebius
>> Date: Thu Jan 23 01:24:47 2020
>> New Revision: 357004
>> URL: https://svnweb.freebsd.org/changeset/base/357004
>>
>> Log:
>> Enter the network epoch for interrupt handlers of INTR_TYPE_NET.
>> Provide tunable to limit how many times handlers may be executed
>> without reentering epoch.
>> Differential Revision: https://reviews.freebsd.org/D23242
>>
>> Modified:
>> head/sys/kern/kern_intr.c
>> head/sys/sys/interrupt.h
>>
>> Modified: head/sys/kern/kern_intr.c
>> ==============================================================================
>>
>> --- head/sys/kern/kern_intr.c Thu Jan 23 01:20:59 2020 (r357003)
>> +++ head/sys/kern/kern_intr.c Thu Jan 23 01:24:47 2020 (r357004)
>> @@ -48,6 +48,7 @@ __FBSDID("$FreeBSD$");
>> #include <sys/mutex.h>
>> #include <sys/priv.h>
>> #include <sys/proc.h>
>> +#include <sys/epoch.h>
>> #include <sys/random.h>
>> #include <sys/resourcevar.h>
>> #include <sys/sched.h>
>> @@ -94,6 +95,9 @@ static int intr_storm_threshold = 0;
>> SYSCTL_INT(_hw, OID_AUTO, intr_storm_threshold, CTLFLAG_RWTUN,
>> &intr_storm_threshold, 0,
>> "Number of consecutive interrupts before storm protection is
>> enabled");
>> +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)");
>> static TAILQ_HEAD(, intr_event) event_list =
>> TAILQ_HEAD_INITIALIZER(event_list);
>> static struct mtx event_lock;
>> @@ -587,6 +591,8 @@ intr_event_add_handler(struct intr_event *ie,
>> const ch
>> ih->ih_flags |= IH_MPSAFE;
>> if (flags & INTR_ENTROPY)
>> ih->ih_flags |= IH_ENTROPY;
>> + if (flags & INTR_TYPE_NET)
>> + ih->ih_flags |= IH_NET;
>> /* We can only have one exclusive handler in a event. */
>> mtx_lock(&ie->ie_lock);
>> @@ -1196,11 +1202,12 @@ ithread_execute_handlers(struct proc *p,
>> struct intr_e
>> static void
>> ithread_loop(void *arg)
>> {
>> + struct epoch_tracker et;
>> struct intr_thread *ithd;
>> struct intr_event *ie;
>> struct thread *td;
>> struct proc *p;
>> - int wake;
>> + int wake, epoch_count;
>> td = curthread;
>> p = td->td_proc;
>> @@ -1235,8 +1242,21 @@ ithread_loop(void *arg)
>> * that the load of ih_need in ithread_execute_handlers()
>> * is ordered after the load of it_need here.
>> */
>> - while (atomic_cmpset_acq_int(&ithd->it_need, 1, 0) != 0)
>> + if (ie->ie_hflags & IH_NET) {
>> + epoch_count = 0;
>> + NET_EPOCH_ENTER(et);
>> + }
>> + while (atomic_cmpset_acq_int(&ithd->it_need, 1, 0) != 0) {
>> ithread_execute_handlers(p, ie);
>> + if ((ie->ie_hflags & IH_NET) &&
>> + ++epoch_count >= intr_epoch_batch) {
>> + NET_EPOCH_EXIT(et);
>> + epoch_count = 0;
>> + NET_EPOCH_ENTER(et);
>> + }
>> + }
>> + if (ie->ie_hflags & IH_NET)
>> + NET_EPOCH_EXIT(et);
>> WITNESS_WARN(WARN_PANIC, NULL, "suspending ithread");
>> mtx_assert(&Giant, MA_NOTOWNED);
Hi Gleb,
What you want to do here is right, but how it is implemented is wrong,
in my opinion.
1) Remove intr_epoch_batch. Most network drivers use interrupt
moderation, and a timeout of 1000 iterations can easily become 1 second
under heavly load !
2) You need to make a new request function for interrupts which take a
pointer to an EPOCH and replace that IH_NET in hflags!
--HPS
More information about the svn-src-all
mailing list