[libvirt] [PATCH 03/11] qemu: Implement the ability to return IOThread stats
John Ferlan
jferlan at redhat.com
Sun Oct 7 13:00:16 UTC 2018
Process the IOThreads polling stats if available. Generate the
output params record to be returned to the caller with the three
values - poll-max-ns, poll-grow, and poll-shrink.
Signed-off-by: John Ferlan <jferlan at redhat.com>
---
include/libvirt/libvirt-domain.h | 1 +
src/libvirt-domain.c | 38 ++++++++++++++++
src/qemu/qemu_driver.c | 78 ++++++++++++++++++++++++++++++++
3 files changed, 117 insertions(+)
diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
index fdd2d6b8ea..58fd4bc10c 100644
--- a/include/libvirt/libvirt-domain.h
+++ b/include/libvirt/libvirt-domain.h
@@ -2048,6 +2048,7 @@ typedef enum {
VIR_DOMAIN_STATS_INTERFACE = (1 << 4), /* return domain interfaces info */
VIR_DOMAIN_STATS_BLOCK = (1 << 5), /* return domain block info */
VIR_DOMAIN_STATS_PERF = (1 << 6), /* return domain perf event info */
+ VIR_DOMAIN_STATS_IOTHREAD = (1 << 7), /* return iothread poll info */
} virDomainStatsTypes;
typedef enum {
diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
index 7690339521..9fda56d660 100644
--- a/src/libvirt-domain.c
+++ b/src/libvirt-domain.c
@@ -11499,6 +11499,44 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
* long long. It is produced by the
* emulation_faults perf event
*
+ * VIR_DOMAIN_STATS_IOTHREAD:
+ * Return IOThread statistics if available. IOThread polling is a
+ * timing mechanism that allows the hypervisor to generate a longer
+ * period of time in which the guest will perform operations on the
+ * CPU being used by the IOThread. The higher the value for poll-max-ns
+ * the longer the guest will keep the CPU. This may affect other host
+ * threads using the CPU. The poll-grow and poll-shrink values allow
+ * the hypervisor to generate a mechanism to add or remove polling time
+ * within the confines of 0 and poll-max-ns. For QEMU, the poll-grow is
+ * multiplied by the polling interval, while poll-shrink is used as a
+ * divisor. When not provided, QEMU may double the polling time until
+ * poll-max-ns is reached. When poll-shrink is 0 (zero) QEMU may reset
+ * the polling interval to 0 until it finds its "sweet spot". Setting
+ * poll-grow too large may cause frequent fluctution of the time; however,
+ * this can be tempered by a high poll-shrink to reduce the polling
+ * interval. For example, a poll-grow of 3 will triple the polling time
+ * which could quickly exceed poll-max-ns; however, a poll-shrink of
+ * 10 would cut that polling time more gradually.
+ *
+ * The typed parameter keys are in this format:
+ *
+ * "iothread.cnt" - maximum number of IOThreads in the subsequent list
+ * as unsigned int. Each IOThread in the list will
+ * will use it's iothread_id value as the <id>. There
+ * may be fewer <id> entries than the iothread.cnt
+ * value if the polling values are not supported.
+ * "iothread.<id>.poll-max-ns" - maximum polling time in ns as an unsigned
+ * long long. A 0 (zero) means polling is
+ * disabled.
+ * "iothread.<id>.poll-grow" - polling time factor as an unsigned int.
+ * A 0 (zero) indicates to allow the underlying
+ * hypervisor to choose how to grow the
+ * polling time.
+ * "iothread.<id>.poll-shrink" - polling time divisor as an unsigned int.
+ * A 0 (zero) indicates to allow the underlying
+ * hypervisor to choose how to shrink the
+ * polling time.
+ *
* Note that entire stats groups or individual stat fields may be missing from
* the output in case they are not supported by the given hypervisor, are not
* applicable for the current state of the guest domain, or their retrieval
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index e0edb43557..ff87865fe6 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -20431,6 +20431,83 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver,
#undef QEMU_ADD_NAME_PARAM
+#define QEMU_ADD_IOTHREAD_PARAM_UI(record, maxparams, id, name, value) \
+ do { \
+ char param_name[VIR_TYPED_PARAM_FIELD_LENGTH]; \
+ snprintf(param_name, VIR_TYPED_PARAM_FIELD_LENGTH, \
+ "block.%u.%s", id, name); \
+ if (virTypedParamsAddUInt(&(record)->params, \
+ &(record)->nparams, \
+ maxparams, \
+ param_name, \
+ value) < 0) \
+ goto cleanup; \
+ } while (0)
+
+#define QEMU_ADD_IOTHREAD_PARAM_ULL(record, maxparams, id, name, value) \
+do { \
+ char param_name[VIR_TYPED_PARAM_FIELD_LENGTH]; \
+ snprintf(param_name, VIR_TYPED_PARAM_FIELD_LENGTH, \
+ "iothread.%u.%s", id, name); \
+ if (virTypedParamsAddULLong(&(record)->params, \
+ &(record)->nparams, \
+ maxparams, \
+ param_name, \
+ value) < 0) \
+ goto cleanup; \
+} while (0)
+
+static int
+qemuDomainGetStatsIOThread(virQEMUDriverPtr driver,
+ virDomainObjPtr dom,
+ virDomainStatsRecordPtr record,
+ int *maxparams,
+ unsigned int privflags ATTRIBUTE_UNUSED)
+{
+ size_t i;
+ qemuMonitorIOThreadInfoPtr *iothreads = NULL;
+ int niothreads;
+ int ret = -1;
+
+ if ((niothreads = qemuDomainGetIOThreadsMon(driver, dom, &iothreads)) < 0)
+ return -1;
+
+ if (niothreads == 0)
+ return 0;
+
+ QEMU_ADD_COUNT_PARAM(record, maxparams, "iothread", niothreads);
+
+ for (i = 0; i < niothreads; i++) {
+ if (iothreads[i]->poll_valid) {
+ QEMU_ADD_IOTHREAD_PARAM_ULL(record, maxparams,
+ iothreads[i]->iothread_id,
+ "poll-max-ns",
+ iothreads[i]->poll_max_ns);
+ QEMU_ADD_IOTHREAD_PARAM_UI(record, maxparams,
+ iothreads[i]->iothread_id,
+ "poll-grow",
+ iothreads[i]->poll_grow);
+ QEMU_ADD_IOTHREAD_PARAM_UI(record, maxparams,
+ iothreads[i]->iothread_id,
+ "poll-shrink",
+ iothreads[i]->poll_shrink);
+ }
+ }
+
+ ret = 0;
+
+ cleanup:
+ for (i = 0; i < niothreads; i++)
+ VIR_FREE(iothreads[i]);
+ VIR_FREE(iothreads);
+
+ return ret;
+}
+
+#undef QEMU_ADD_IOTHREAD_PARAM_UI
+
+#undef QEMU_ADD_IOTHREAD_PARAM_ULL
+
#undef QEMU_ADD_COUNT_PARAM
static int
@@ -20505,6 +20582,7 @@ static struct qemuDomainGetStatsWorker qemuDomainGetStatsWorkers[] = {
{ qemuDomainGetStatsInterface, VIR_DOMAIN_STATS_INTERFACE, false },
{ qemuDomainGetStatsBlock, VIR_DOMAIN_STATS_BLOCK, true },
{ qemuDomainGetStatsPerf, VIR_DOMAIN_STATS_PERF, false },
+ { qemuDomainGetStatsIOThread, VIR_DOMAIN_STATS_IOTHREAD, false },
{ NULL, 0, false }
};
--
2.17.1
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