[libvirt] [PATCHv3 08/10] threshold: scrape threshold data from QMP
Eric Blake
eblake at redhat.com
Mon Jun 22 23:06:44 UTC 2015
Expose threshold information by collecting the information from
QMP commands. qemu 2.3 has a way to get threshold information
on all elements of a block chain, but only when node names are
used - what's worse, the threshold information is only provided
by 'query-named-block-nodes', but the mapping between devices
and nodes is only provided by 'query-blockstats'. Rather than
manage node names ourselves, we rely on qemu 2.4 doing auto
naming; then when collecting the stats, we make a pass through
both query functions.
I chose to go with the naive O(n^2) mapping algorithm; if it turns
out to be slow in practice on a guest with lots of nodes, we can
enhance it via a sorted list or hash table lookup.
* src/qemu/qemu_monitor.h (qemuMonitorBlockStatsUpdateThreshold):
New prototype.
* src/qemu/qemu_monitor.c (qemuMonitorBlockStatsUpdateThreshold):
New function.
* src/qemu/qemu_monitor_json.h
(qemuMonitorJSONBlockStatsUpdateThreshold): New prototype.
* src/qemu/qemu_monitor_json.c (qemuMonitorJSONDevGetBlockExtent):
Populate node name.
(qemuMonitorJSONBlockStatsUpdateThreshold)
(qemuMonitorJSONBlockStatsUpdateOneThreshold): Use it to populate
threshold data.
(qemuMonitorJSONGetOneBlockStatsInfo)
(qemuMonitorJSONGetBlockExtent): Update callers.
* src/qemu/qemu_driver.c (qemuDomainGetStatsOneBlock): Expose
threshold data.
Signed-off-by: Eric Blake <eblake at redhat.com>
---
src/qemu/qemu_driver.c | 12 ++++-
src/qemu/qemu_monitor.c | 13 ++++++
src/qemu/qemu_monitor.h | 4 ++
src/qemu/qemu_monitor_json.c | 102 ++++++++++++++++++++++++++++++++++++++-----
src/qemu/qemu_monitor_json.h | 2 +
5 files changed, 121 insertions(+), 12 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 25bc76d..72e256b 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -19282,6 +19282,12 @@ qemuDomainGetStatsOneBlock(virQEMUDriverPtr driver,
QEMU_ADD_BLOCK_PARAM_LL(record, maxparams, block_idx,
"fl.times", entry->flush_total_times);
+ /* TODO: Until we can set thresholds on backing elements, we only
+ * report the threshold on the active layer. */
+ if (!backing_idx)
+ QEMU_ADD_BLOCK_PARAM_ULL(record, maxparams, block_idx,
+ "write-threshold", entry->write_threshold);
+
QEMU_ADD_BLOCK_PARAM_ULL(record, maxparams, block_idx,
"allocation", entry->wr_highest_offset);
@@ -19323,9 +19329,13 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver,
qemuDomainObjEnterMonitor(driver, dom);
rc = qemuMonitorGetAllBlockStatsInfo(priv->mon, &stats,
visitBacking);
- if (rc >= 0)
+ if (rc >= 0) {
ignore_value(qemuMonitorBlockStatsUpdateCapacity(priv->mon, stats,
visitBacking));
+ if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_AUTO_NODE_NAMES))
+ ignore_value(qemuMonitorBlockStatsUpdateThreshold(priv->mon,
+ stats));
+ }
if (qemuDomainObjExitMonitor(driver, dom) < 0)
goto cleanup;
diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index 86dc4be..a3ad740 100644
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -1838,6 +1838,19 @@ qemuMonitorBlockStatsUpdateCapacity(qemuMonitorPtr mon,
}
+/* Updates "stats" to fill write threshold of the image */
+int
+qemuMonitorBlockStatsUpdateThreshold(qemuMonitorPtr mon,
+ virHashTablePtr stats)
+{
+ VIR_DEBUG("stats=%p", stats);
+
+ QEMU_CHECK_MONITOR_JSON(mon);
+
+ return qemuMonitorJSONBlockStatsUpdateThreshold(mon, stats);
+}
+
+
int
qemuMonitorGetBlockExtent(qemuMonitorPtr mon,
const char *dev_name,
diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
index c0ea2ee..541f774 100644
--- a/src/qemu/qemu_monitor.h
+++ b/src/qemu/qemu_monitor.h
@@ -395,6 +395,10 @@ int qemuMonitorBlockStatsUpdateCapacity(qemuMonitorPtr mon,
bool backingChain)
ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
+int qemuMonitorBlockStatsUpdateThreshold(qemuMonitorPtr mon,
+ virHashTablePtr stats)
+ ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
+
int qemuMonitorGetBlockExtent(qemuMonitorPtr mon,
const char *dev_name,
unsigned long long *extent);
diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index 32b2719..885b6f4 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -1668,9 +1668,13 @@ typedef enum {
} qemuMonitorBlockExtentError;
+/* Get the highest written extent. Additionally, if NODE is not null,
+ * and a node name is associated with the extent, then return that
+ * name; but failure to get a node name is not fatal. */
static int
qemuMonitorJSONDevGetBlockExtent(virJSONValuePtr dev,
- unsigned long long *extent)
+ unsigned long long *extent,
+ char **node)
{
virJSONValuePtr stats;
virJSONValuePtr parent;
@@ -1678,6 +1682,11 @@ qemuMonitorJSONDevGetBlockExtent(virJSONValuePtr dev,
if ((parent = virJSONValueObjectGetObject(dev, "parent")) == NULL)
return QEMU_MONITOR_BLOCK_EXTENT_ERROR_NOPARENT;
+ if (node) {
+ const char *name = virJSONValueObjectGetString(parent, "node-name");
+ ignore_value(VIR_STRDUP_QUIET(*node, name));
+ }
+
if ((stats = virJSONValueObjectGetObject(parent, "stats")) == NULL)
return QEMU_MONITOR_BLOCK_EXTENT_ERROR_NOSTATS;
@@ -1725,18 +1734,23 @@ qemuMonitorJSONGetOneBlockStatsInfo(virJSONValuePtr dev,
goto cleanup; \
} \
}
- QEMU_MONITOR_BLOCK_STAT_GET("rd_bytes", bstats->rd_bytes, true);
- QEMU_MONITOR_BLOCK_STAT_GET("wr_bytes", bstats->wr_bytes, true);
- QEMU_MONITOR_BLOCK_STAT_GET("rd_operations", bstats->rd_req, true);
- QEMU_MONITOR_BLOCK_STAT_GET("wr_operations", bstats->wr_req, true);
- QEMU_MONITOR_BLOCK_STAT_GET("rd_total_time_ns", bstats->rd_total_times, false);
- QEMU_MONITOR_BLOCK_STAT_GET("wr_total_time_ns", bstats->wr_total_times, false);
- QEMU_MONITOR_BLOCK_STAT_GET("flush_operations", bstats->flush_req, false);
- QEMU_MONITOR_BLOCK_STAT_GET("flush_total_time_ns", bstats->flush_total_times, false);
+ QEMU_MONITOR_BLOCK_STAT_GET("rd_bytes", bstats->rd_bytes, true);
+ QEMU_MONITOR_BLOCK_STAT_GET("wr_bytes", bstats->wr_bytes, true);
+ QEMU_MONITOR_BLOCK_STAT_GET("rd_operations", bstats->rd_req, true);
+ QEMU_MONITOR_BLOCK_STAT_GET("wr_operations", bstats->wr_req, true);
+ QEMU_MONITOR_BLOCK_STAT_GET("rd_total_time_ns", bstats->rd_total_times,
+ false);
+ QEMU_MONITOR_BLOCK_STAT_GET("wr_total_time_ns", bstats->wr_total_times,
+ false);
+ QEMU_MONITOR_BLOCK_STAT_GET("flush_operations", bstats->flush_req,
+ false);
+ QEMU_MONITOR_BLOCK_STAT_GET("flush_total_time_ns",
+ bstats->flush_total_times, false);
#undef QEMU_MONITOR_BLOCK_STAT_GET
/* it's ok to not have this information here. Just skip silently. */
- qemuMonitorJSONDevGetBlockExtent(dev, &bstats->wr_highest_offset);
+ qemuMonitorJSONDevGetBlockExtent(dev, &bstats->wr_highest_offset,
+ &bstats->allocation_node);
if (virHashAddEntry(hash, entry_name, bstats) < 0)
goto cleanup;
@@ -1937,6 +1951,72 @@ qemuMonitorJSONBlockStatsUpdateCapacity(qemuMonitorPtr mon,
}
+/* Hash table callback: Best effort routine to update write-threshold
+ * of a given qemuBlockStatsPtr (payload) using the QMP results for
+ * all nodes (opaque). */
+static void
+qemuMonitorJSONBlockStatsUpdateOneThreshold(void *payload,
+ const void *entry ATTRIBUTE_UNUSED,
+ void *opaque)
+{
+ qemuBlockStatsPtr data = payload;
+ virJSONValuePtr nodes = opaque;
+ size_t i;
+
+ if (!data->allocation_node)
+ return;
+ for (i = 0; i < virJSONValueArraySize(nodes); i++) {
+ virJSONValuePtr node = virJSONValueArrayGet(nodes, i);
+ const char *name = virJSONValueObjectGetString(node, "node-name");
+
+ if (STREQ_NULLABLE(data->allocation_node, name) &&
+ virJSONValueObjectGetNumberUlong(node, "write_threshold",
+ &data->write_threshold) == 0)
+ break;
+ }
+}
+
+
+int
+qemuMonitorJSONBlockStatsUpdateThreshold(qemuMonitorPtr mon,
+ virHashTablePtr stats)
+{
+ int ret = -1;
+ int rc;
+ virJSONValuePtr cmd;
+ virJSONValuePtr reply = NULL;
+ virJSONValuePtr devices;
+
+ if (!(cmd = qemuMonitorJSONMakeCommand("query-named-block-nodes", NULL)))
+ return -1;
+ if ((rc = qemuMonitorJSONCommand(mon, cmd, &reply)) < 0)
+ goto cleanup;
+ if (qemuMonitorJSONCheckError(cmd, reply) < 0)
+ goto cleanup;
+
+ if (!(devices = virJSONValueObjectGetArray(reply, "return"))) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("query-named-block-nodes reply was missing list"));
+ goto cleanup;
+ }
+ /* O(n^2) collection pass because we visit the entire nodes list
+ * for each stats entry. Hopefully there aren't a boat-load of
+ * nodes to make this noticeably slower. If we need, we can do a
+ * pre-processing pass over devices to reach O(n log n) (via
+ * sorted list) or amortized O(n) (via a hash table) layout where
+ * node name lookup is more efficient. */
+ if (virJSONValueArraySize(devices) > 0)
+ virHashForEach(stats, qemuMonitorJSONBlockStatsUpdateOneThreshold,
+ devices);
+ ret = 0;
+
+ cleanup:
+ virJSONValueFree(cmd);
+ virJSONValueFree(reply);
+ return ret;
+}
+
+
static int
qemuMonitorJSONReportBlockExtentError(qemuMonitorBlockExtentError error)
{
@@ -2025,7 +2105,7 @@ int qemuMonitorJSONGetBlockExtent(qemuMonitorPtr mon,
continue;
found = true;
- if ((err = qemuMonitorJSONDevGetBlockExtent(dev, extent)) !=
+ if ((err = qemuMonitorJSONDevGetBlockExtent(dev, extent, NULL)) !=
QEMU_MONITOR_BLOCK_EXTENT_ERROR_OK) {
qemuMonitorJSONReportBlockExtentError(err);
goto cleanup;
diff --git a/src/qemu/qemu_monitor_json.h b/src/qemu/qemu_monitor_json.h
index f18295b..2f90b5c 100644
--- a/src/qemu/qemu_monitor_json.h
+++ b/src/qemu/qemu_monitor_json.h
@@ -77,6 +77,8 @@ int qemuMonitorJSONGetAllBlockStatsInfo(qemuMonitorPtr mon,
int qemuMonitorJSONBlockStatsUpdateCapacity(qemuMonitorPtr mon,
virHashTablePtr stats,
bool backingChain);
+int qemuMonitorJSONBlockStatsUpdateThreshold(qemuMonitorPtr mon,
+ virHashTablePtr stats);
int qemuMonitorJSONGetBlockExtent(qemuMonitorPtr mon,
const char *dev_name,
unsigned long long *extent);
--
2.4.3
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