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authorMike Belopuhov <mikeb@cvs.openbsd.org>2016-07-29 21:27:44 +0000
committerMike Belopuhov <mikeb@cvs.openbsd.org>2016-07-29 21:27:44 +0000
commit9443416a012ae581ae520d03d097b04711b09a0f (patch)
treea3e7ca0f8c30e7c8bb8eb19fe1cf35e963090c9d /sys/dev/pv/xen.c
parent10b75e0a2ac72173dbfc87711ce38e501d85cdc6 (diff)
Move xen interrupt handlers to dedicated task queues
Handling receive and transmit for multiple networking interfaces in a "shared interrupt" within normal interrupt vector code path introduces too much delay from the hypervisor POV which prevents it from injecting further completion event interrupts for Rx and Tx queues. Additionally, Netfront backend driver includes a mechanism to detect Rx ring stalls and "turn the carrier off" when the guest is not replenishing the ring (e.g. due to missing completion interrupts) that relies on guest waking up periodically and making sure that the Rx ring completion handling is progressing. Having tried both task queue + timeout and interrupts + timeout approaches, it appears that using the task queue is more flexible and provides superior performance under heavy network load.
Diffstat (limited to 'sys/dev/pv/xen.c')
-rw-r--r--sys/dev/pv/xen.c26
1 files changed, 21 insertions, 5 deletions
diff --git a/sys/dev/pv/xen.c b/sys/dev/pv/xen.c
index 6e13b129688..d534be964a4 100644
--- a/sys/dev/pv/xen.c
+++ b/sys/dev/pv/xen.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: xen.c,v 1.56 2016/04/28 16:40:10 mikeb Exp $ */
+/* $OpenBSD: xen.c,v 1.57 2016/07/29 21:27:43 mikeb Exp $ */
/*
* Copyright (c) 2015 Mike Belopuhov
@@ -642,13 +642,22 @@ xen_intr(void)
continue;
}
xi->xi_evcnt.ec_count++;
- if (xi->xi_handler)
- xi->xi_handler(xi->xi_arg);
+ task_add(xi->xi_taskq, &xi->xi_task);
}
}
}
void
+xen_intr_schedule(xen_intr_handle_t xih)
+{
+ struct xen_softc *sc = xen_sc;
+ struct xen_intsrc *xi;
+
+ if ((xi = xen_lookup_intsrc(sc, (evtchn_port_t)xih)) != NULL)
+ task_add(xi->xi_taskq, &xi->xi_task);
+}
+
+void
xen_intr_signal(xen_intr_handle_t xih)
{
struct xen_softc *sc = xen_sc;
@@ -685,10 +694,17 @@ xen_intr_establish(evtchn_port_t port, xen_intr_handle_t *xih, int domain,
if (xi == NULL)
return (-1);
- xi->xi_handler = handler;
- xi->xi_arg = arg;
xi->xi_port = (evtchn_port_t)*xih;
+ xi->xi_taskq = taskq_create(name, 1, IPL_NET, TASKQ_MPSAFE);
+ if (!xi->xi_taskq) {
+ printf("%s: failed to create interrupt task for %s\n",
+ sc->sc_dev.dv_xname, name);
+ free(xi, M_DEVBUF, sizeof(*xi));
+ return (-1);
+ }
+ task_set(&xi->xi_task, handler, arg);
+
if (port == 0) {
/* We're being asked to allocate a new event port */
memset(&eau, 0, sizeof(eau));