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Enter the network epoch for interrupt handlers of INTR_TYPE_NET.

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Provide tunable to limit how many times handlers may be executed
without reentering epoch.

Differential Revision:	https://reviews.freebsd.org/D23242
This commit is contained in:
Gleb Smirnoff 2020-01-23 01:24:47 +00:00
parent c4eb66309f
commit 511d1afb6b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=357004
2 changed files with 23 additions and 2 deletions
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24
sys/kern/kern_intr.c
View File

@ -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 char *name,
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_event *ie)
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);

1
sys/sys/interrupt.h
View File

@ -58,6 +58,7 @@ struct intr_handler {
};
/* Interrupt handle flags kept in ih_flags */
#define IH_NET 0x00000001 /* Network. */
#define IH_EXCLUSIVE 0x00000002 /* Exclusive interrupt. */
#define IH_ENTROPY 0x00000004 /* Device is a good entropy source. */
#define IH_DEAD 0x00000008 /* Handler should be removed. */