@@ -51,12 +51,20 @@ static const int if_max_devs[IF_COUNT] = {
[IF_SCSI] = 7,
};
+enum {
+ SLICE_TIME_NS = 100000000, /* 100 ms rate-limiting slice time */
+};
+
typedef struct StreamState {
MonitorCompletion *cancel_cb;
void *cancel_opaque;
int64_t offset; /* current position in block device */
BlockDriverState *bs;
QEMUTimer *timer;
+ int64_t bytes_per_sec; /* rate limit */
+ int64_t bytes_per_slice; /* rate limit scaled to slice */
+ int64_t slice_end_time; /* when this slice finishes */
+ int64_t slice_start_offset; /* offset when slice started */
QLIST_ENTRY(StreamState) list;
} StreamState;
@@ -71,7 +79,7 @@ static QObject *stream_get_qobject(StreamState *s)
return qobject_from_jsonf("{ 'device': %s, 'type': 'stream', "
"'offset': %" PRId64 ", 'len': %" PRId64 ", "
"'speed': %" PRId64 " }",
- name, s->offset, len, (int64_t)0);
+ name, s->offset, len, s->bytes_per_sec);
}
static void stream_mon_event(StreamState *s, int ret)
@@ -107,6 +115,27 @@ static void stream_complete(StreamState *s, int ret)
stream_free(s);
}
+static void stream_schedule_next_iteration(StreamState *s)
+{
+ int64_t next = qemu_get_clock_ns(rt_clock);
+
+ /* New slice */
+ if (next >= s->slice_end_time) {
+ s->slice_end_time = next + SLICE_TIME_NS;
+ s->slice_start_offset = s->offset;
+ }
+
+ /* Throttle */
+ if (s->bytes_per_slice &&
+ s->offset - s->slice_start_offset >= s->bytes_per_slice) {
+ next = s->slice_end_time;
+ s->slice_end_time = next + SLICE_TIME_NS;
+ s->slice_start_offset += s->bytes_per_slice;
+ }
+
+ qemu_mod_timer(s->timer, next);
+}
+
static void stream_cb(void *opaque, int nb_sectors)
{
StreamState *s = opaque;
@@ -124,7 +153,7 @@ static void stream_cb(void *opaque, int nb_sectors)
} else if (s->cancel_cb) {
stream_free(s);
} else {
- qemu_mod_timer(s->timer, qemu_get_clock_ns(rt_clock));
+ stream_schedule_next_iteration(s);
}
}
@@ -202,6 +231,20 @@ static int stream_stop(const char *device, MonitorCompletion *cb, void *opaque)
return 0;
}
+static int stream_set_speed(const char *device, int64_t bytes_per_sec)
+{
+ StreamState *s = stream_find(device);
+
+ if (!s) {
+ qerror_report(QERR_DEVICE_NOT_ACTIVE, device);
+ return -1;
+ }
+
+ s->bytes_per_sec = bytes_per_sec;
+ s->bytes_per_slice = bytes_per_sec * SLICE_TIME_NS / 1000000000LL;
+ return 0;
+}
+
/*
* We automatically delete the drive when a device using it gets
* unplugged. Questionable feature, but we can't just drop it.
@@ -814,7 +857,7 @@ static void monitor_print_block_stream(Monitor *mon, const QObject *data)
qdict_get_str(stream, "device"),
qdict_get_int(stream, "offset"),
qdict_get_int(stream, "len"),
- (int64_t)0);
+ qdict_get_int(stream, "speed"));
}
void monitor_print_block_jobs(Monitor *mon, const QObject *data)
@@ -863,6 +906,20 @@ int do_block_job_cancel(Monitor *mon, const QDict *params,
return stream_stop(device, cb, opaque);
}
+int do_block_job_set_speed(Monitor *mon, const QDict *params,
+ QObject **ret_data)
+{
+ const char *device = qdict_get_str(params, "device");
+ int64_t value;
+
+ value = qdict_get_int(params, "value");
+ if (value < 0) {
+ value = 0;
+ }
+
+ return stream_set_speed(device, value);
+}
+
static int eject_device(Monitor *mon, BlockDriverState *bs, int force)
{
if (!force) {
@@ -71,5 +71,7 @@ void do_info_block_jobs(Monitor *mon, QObject **ret_data);
int do_block_stream(Monitor *mon, const QDict *params, QObject **ret_data);
int do_block_job_cancel(Monitor *mon, const QDict *params,
MonitorCompletion cb, void *opaque);
+int do_block_job_set_speed(Monitor *mon, const QDict *params,
+ QObject **ret_data);
#endif
@@ -67,6 +67,20 @@ Stop an active block streaming operation.
ETEXI
{
+ .name = "block_job_set_speed",
+ .args_type = "device:B,value:o",
+ .params = "device value",
+ .help = "Set the maximum speed for a background block operation",
+ .mhandler.cmd_new = do_block_job_set_speed,
+ },
+
+STEXI
+@item block_job_set_speed @var{device} @var{value}
+@findex block_job_set_speed
+Set the maximum speed for a background block operation.
+ETEXI
+
+ {
.name = "q|quit",
.args_type = "",
.params = "",
@@ -1051,6 +1051,41 @@ Examples:
EQMP
{
+ .name = "block_job_set_speed",
+ .args_type = "device:B,value:o",
+ .params = "device value",
+ .help = "Set maximum speed for a background block operation",
+ .mhandler.cmd_new = do_block_job_set_speed,
+ },
+
+SQMP
+block_job_set_speed
+-------------------
+
+Set maximum speed for a background block operation.
+
+This is a per-block device command that can only be issued
+when there is an active block job.
+
+Throttling can be disabled by setting the speed to 0.
+
+Arguments:
+
+- device: device name (json-string)
+- value: maximum speed, in bytes per second (json-int)
+
+Errors:
+DeviceNotActive: streaming is not active on this device
+NotSupported: job type does not support speed setting
+
+Example:
+
+-> { "execute": "block_job_set_speed",
+ "arguments": { "device": "virtio0", "value": 1024 } }
+
+EQMP
+
+ {
.name = "qmp_capabilities",
.args_type = "",
.params = "",
The block_job_set_speed command sets a throughput limit on an active image streaming operation. This can be used to isolate the streaming operation and control the amount of I/O bandwidth it consumes. The command synopsis is as follows: block_job_set_speed ------------------- Set maximum speed for a background block operation. This is a per-block device command that can only be issued when there is an active block job. Throttling can be disabled by setting the speed to 0. Arguments: - device: device name (json-string) - value: maximum speed, in bytes per second (json-int) Errors: DeviceNotActive: streaming is not active on this device NotSupported: job type does not support speed setting Example: -> { "execute": "block_job_set_speed", "arguments": { "device": "virtio0", "value": 1024 } } Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> --- blockdev.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++-- blockdev.h | 2 + hmp-commands.hx | 14 ++++++++++++ qmp-commands.hx | 35 ++++++++++++++++++++++++++++++ 4 files changed, 111 insertions(+), 3 deletions(-)