Re: [libvirt] [PATCH 03/11] qemu: Implement the ability to return IOThread stats

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(a)redhat.com&gt; --- 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 } };