Author: sephe
Date: Mon Oct 17 07:35:31 2016
New Revision: 307493
URL: https://svnweb.freebsd.org/changeset/base/307493
Log:
MFC 305111
hyperv/timesync: Rework time adjustment policy
- By default, adjust time upon SYNC request. It can be disabled
through hw.hvtimesync.ignore_sync_req. SYNC request will be
sent by hypervisor the host is resumed, rebooted, etc.
- By default, adjust time upon SAMPLE request, if there is 100ms
difference between VM time and hypervisor time. This can be
disabled through hw.hvtimesync.sample_drift.
And nuke the unnecessary task, since channel callback is running
in a Hyper-V taskqueue nowadays.
Submitted by: YanZhe Chen <t-yachen microsoft com>
Discussed with: Dexuan Cui <decui microsoft com>, Hongjiang Zhang
<honzhan microsoft com>, sephe
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D7707
Modified:
stable/11/sys/dev/hyperv/utilities/hv_timesync.c
Directory Properties:
stable/11/ (props changed)
Modified: stable/11/sys/dev/hyperv/utilities/hv_timesync.c
==============================================================================
--- stable/11/sys/dev/hyperv/utilities/hv_timesync.c Mon Oct 17 07:32:49
2016 (r307492)
+++ stable/11/sys/dev/hyperv/utilities/hv_timesync.c Mon Oct 17 07:35:31
2016 (r307493)
@@ -39,7 +39,7 @@
#include <sys/timetc.h>
#include <sys/syscallsubr.h>
#include <sys/systm.h>
-#include <sys/taskqueue.h>
+#include <sys/sysctl.h>
#include <dev/hyperv/include/hyperv.h>
#include <dev/hyperv/include/vmbus.h>
@@ -52,11 +52,7 @@
#define HV_ICTIMESYNCFLAG_SYNC 1
#define HV_ICTIMESYNCFLAG_SAMPLE 2
#define HV_NANO_SEC_PER_SEC 1000000000
-
-/* Time Sync data */
-typedef struct {
- uint64_t data;
-} time_sync_data;
+#define HV_NANO_SEC_PER_MILLI_SEC 1000000
static const struct vmbus_ic_desc vmbus_timesync_descs[] = {
{
@@ -75,22 +71,43 @@ struct hv_ictimesync_data {
uint8_t flags;
} __packed;
-typedef struct hv_timesync_sc {
- hv_util_sc util_sc;
- struct task task;
- time_sync_data time_msg;
-} hv_timesync_sc;
+/*
+ * Globals
+ */
+SYSCTL_NODE(_hw, OID_AUTO, hvtimesync, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
+ "Hyper-V timesync interface");
+
+/* Ignore the sync request when set to 1. */
+static int ignore_sync_req = 0;
+SYSCTL_INT(_hw_hvtimesync, OID_AUTO, ignore_sync_req, CTLFLAG_RWTUN,
+ &ignore_sync_req, 0,
+ "Ignore the sync request when set to 1.");
+
+/*
+ * Trigger sample sync when drift exceeds threshold (ms).
+ * Ignore the sample request when set to 0.
+ */
+static int sample_drift = 100;
+SYSCTL_INT(_hw_hvtimesync, OID_AUTO, sample_drift, CTLFLAG_RWTUN,
+ &sample_drift, 0,
+ "Threshold that makes sample request trigger the sync.");
/**
- * Set host time based on time sync message from host
+ * @brief Synchronize time with host after reboot, restore, etc.
+ *
+ * ICTIMESYNCFLAG_SYNC flag bit indicates reboot, restore events of the VM.
+ * After reboot the flag ICTIMESYNCFLAG_SYNC is included in the first time
+ * message after the timesync channel is opened. Since the hv_utils module is
+ * loaded after hv_vmbus, the first message is usually missed. The other
+ * thing is, systime is automatically set to emulated hardware clock which may
+ * not be UTC time or in the same time zone. So, to override these effects, we
+ * use the first 50 time samples for initial system time setting.
*/
-static void
-hv_set_host_time(void *context, int pending)
+static inline
+void hv_adj_guesttime(hv_util_sc *sc, uint64_t hosttime, uint8_t flags)
{
- hv_timesync_sc *softc = (hv_timesync_sc*)context;
- uint64_t hosttime = softc->time_msg.data;
struct timespec guest_ts, host_ts;
- uint64_t host_tns;
+ uint64_t host_tns, guest_tns;
int64_t diff;
int error;
@@ -99,37 +116,35 @@ hv_set_host_time(void *context, int pend
host_ts.tv_nsec = (long)(host_tns%HV_NANO_SEC_PER_SEC);
nanotime(&guest_ts);
+ guest_tns = guest_ts.tv_sec * HV_NANO_SEC_PER_SEC + guest_ts.tv_nsec;
- diff = (int64_t)host_ts.tv_sec - (int64_t)guest_ts.tv_sec;
+ if ((flags & HV_ICTIMESYNCFLAG_SYNC) != 0 && ignore_sync_req == 0) {
+ if (bootverbose) {
+ device_printf(sc->ic_dev, "handle sync request "
+ "{host: %ju, guest: %ju}\n",
+ (uintmax_t)host_tns, (uintmax_t)guest_tns);
+ }
- /*
- * If host differs by 5 seconds then make the guest catch up
- */
- if (diff > 5 || diff < -5) {
error = kern_clock_settime(curthread, CLOCK_REALTIME,
&host_ts);
+ return;
}
-}
-/**
- * @brief Synchronize time with host after reboot, restore, etc.
- *
- * ICTIMESYNCFLAG_SYNC flag bit indicates reboot, restore events of the VM.
- * After reboot the flag ICTIMESYNCFLAG_SYNC is included in the first time
- * message after the timesync channel is opened. Since the hv_utils module is
- * loaded after hv_vmbus, the first message is usually missed. The other
- * thing is, systime is automatically set to emulated hardware clock which may
- * not be UTC time or in the same time zone. So, to override these effects, we
- * use the first 50 time samples for initial system time setting.
- */
-static inline
-void hv_adj_guesttime(hv_timesync_sc *sc, uint64_t hosttime, uint8_t flags)
-{
- sc->time_msg.data = hosttime;
-
- if (((flags & HV_ICTIMESYNCFLAG_SYNC) != 0) ||
- ((flags & HV_ICTIMESYNCFLAG_SAMPLE) != 0)) {
- taskqueue_enqueue(taskqueue_thread, &sc->task);
+ if ((flags & HV_ICTIMESYNCFLAG_SAMPLE) != 0 && sample_drift != 0) {
+ if (bootverbose) {
+ device_printf(sc->ic_dev, "handle sample request "
+ "{host: %ju, guest: %ju}\n",
+ (uintmax_t)host_tns, (uintmax_t)guest_tns);
+ }
+
+ diff = (int64_t)(host_tns - guest_tns) /
HV_NANO_SEC_PER_MILLI_SEC;
+ if (diff > sample_drift || diff < -sample_drift) {
+ error = kern_clock_settime(curthread, CLOCK_REALTIME,
+ &host_ts);
+ if (bootverbose)
+ device_printf(sc->ic_dev, "trigger sample
sync");
+ }
+ return;
}
}
@@ -145,12 +160,12 @@ hv_timesync_cb(struct vmbus_channel *cha
int ret;
uint8_t* time_buf;
struct hv_ictimesync_data* timedatap;
- hv_timesync_sc *softc;
+ hv_util_sc *softc;
- softc = (hv_timesync_sc*)context;
- time_buf = softc->util_sc.receive_buffer;
+ softc = (hv_util_sc*)context;
+ time_buf = softc->receive_buffer;
- recvlen = softc->util_sc.ic_buflen;
+ recvlen = softc->ic_buflen;
ret = vmbus_chan_recv(channel, time_buf, &recvlen, &requestId);
KASSERT(ret != ENOBUFS, ("hvtimesync recvbuf is not large enough"));
/* XXX check recvlen to make sure that it contains enough data */
@@ -162,7 +177,7 @@ hv_timesync_cb(struct vmbus_channel *cha
if (icmsghdrp->icmsgtype == HV_ICMSGTYPE_NEGOTIATE) {
int error;
- error = vmbus_ic_negomsg(&softc->util_sc, time_buf, &recvlen);
+ error = vmbus_ic_negomsg(softc, time_buf, &recvlen);
if (error)
return;
} else {
@@ -190,18 +205,12 @@ hv_timesync_probe(device_t dev)
static int
hv_timesync_attach(device_t dev)
{
- hv_timesync_sc *softc = device_get_softc(dev);
-
- TASK_INIT(&softc->task, 1, hv_set_host_time, softc);
return hv_util_attach(dev, hv_timesync_cb);
}
static int
hv_timesync_detach(device_t dev)
{
- hv_timesync_sc *softc = device_get_softc(dev);
-
- taskqueue_drain(taskqueue_thread, &softc->task);
return hv_util_detach(dev);
}
@@ -213,7 +222,7 @@ static device_method_t timesync_methods[
{ 0, 0 }
};
-static driver_t timesync_driver = { "hvtimesync", timesync_methods,
sizeof(hv_timesync_sc)};
+static driver_t timesync_driver = { "hvtimesync", timesync_methods,
sizeof(hv_util_sc)};
static devclass_t timesync_devclass;
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