add new API virDomainGetCPUStats() for getting cpu accounting information per real cpus which is used by a domain. based on ideas by Lai Jiangshan and Eric Blake. Proposed API is a bit morified to be able to return max cpu ID. (max cpu ID != cpu num.) * src/libvirt_public.syms: add API for LIBVIRT_0.9.10 * src/libvirt.c: define virDomainGetCPUStats() * include/libvirt/libvirt.h.in: add virDomainGetCPUStats() header * src/driver.h: add driver API * python/generator.py: add python API (as not implemented) --- include/libvirt/libvirt.h.in | 6 ++ python/generator.py | 1 + src/driver.h | 8 +++ src/libvirt.c | 136 ++++++++++++++++++++++++++++++++++++++++++ src/libvirt_public.syms | 1 + 5 files changed, 152 insertions(+), 0 deletions(-) diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in index e99cd00..e8b5116 100644 --- a/include/libvirt/libvirt.h.in +++ b/include/libvirt/libvirt.h.in @@ -3797,6 +3797,12 @@ int virConnectSetKeepAlive(virConnectPtr conn, int interval, unsigned int count); +int virDomainGetCPUStats(virDomainPtr domain, + virTypedParameterPtr params, + unsigned int nparams, + int start_cpu, + unsigned int ncpus, + unsigned int flags); #ifdef __cplusplus } #endif diff --git a/python/generator.py b/python/generator.py index de635dc..9c74427 100755 --- a/python/generator.py +++ b/python/generator.py @@ -422,6 +422,7 @@ skip_impl = ( 'virDomainGetBlockIoTune', 'virDomainSetInterfaceParameters', 'virDomainGetInterfaceParameters', + 'virDomainGetCPUStats' # not implemented now. ) qemu_skip_impl = ( diff --git a/src/driver.h b/src/driver.h index df2aa60..0e52770 100644 --- a/src/driver.h +++ b/src/driver.h @@ -797,6 +797,13 @@ typedef int (*virDrvDomainShutdownFlags)(virDomainPtr domain, unsigned int flags); +typedef int + (*virDrvDomainGetCPUStats)(virDomainPtr domain, + virTypedParameterPtr params, + unsigned int nparams, + int start_cpu, + unsigned int ncpus, + unsigned int flags); /** * _virDriver: @@ -967,6 +974,7 @@ struct _virDriver { virDrvNodeSuspendForDuration nodeSuspendForDuration; virDrvDomainSetBlockIoTune domainSetBlockIoTune; virDrvDomainGetBlockIoTune domainGetBlockIoTune; + virDrvDomainGetCPUStats domainGetCPUStats; }; typedef int diff --git a/src/libvirt.c b/src/libvirt.c index e9d638b..8983f27 100644 --- a/src/libvirt.c +++ b/src/libvirt.c @@ -18017,3 +18017,139 @@ error: virDispatchError(dom->conn); return -1; } + +/** + * virDomainGetCPUStats: + * @domain: domain to query + * @params: array to populate on output + * @nparams: number of parameters per cpu + * @start_cpu: which cpu to start with, or -1 for summary + * @ncpus: how many cpus to query + * @flags: unused for now + * + * Get statistics relating to CPU usage attributable to a single + * domain (in contrast to the statistics returned by + * virNodeGetCPUStats() for all processes on the host). @dom + * must be running (an inactive domain has no attributable cpu + * usage). On input, @params must contain at least @nparams * @ncpus + * entries, allocated by the caller. + * + * Now, @ncpus is limited to be <= 128. If you want to get + * values in a host with more cpus, you need to call multiple times. + * + * @nparams are limited to be <= 16 but maximum params per cpu + * provided by will be smaller than this. + * + * + * If @start_cpu is -1, then @ncpus must be 1, and the returned + * results reflect the statistics attributable to the entire + * domain (such as user and system time for the process as a + * whole). Otherwise, @start_cpu represents which cpu to start + * with, and @ncpus represents how many consecutive processors to + * query, with statistics attributable per processor (such as + * per-cpu usage). + * + * As a special case, if @params is NULL and @nparams is 0 and + * @ncpus is 1, and the return value will be how many + * statistics are available for the given @start_cpu. This number + * may be different for @start_cpu of -1 than for any non-negative + * value, but will be the same for all non-negative @start_cpu. + * + * And, if @param is NULL and @ncparam is 0 and @ncpus is 0, + * Max cpu id of the node is returned. (considering cpu hotplug, + * max cpu id may be different from the number of cpu on a host.) + * + * For now, @flags is unused, and the statistics all relate to the + * usage from the host perspective; the number of cpus available to + * query can be determined by the cpus member of the result of + * virNodeGetInfo(), even if the domain has had vcpus pinned to only + * use a subset of overall host cpus. It is possible that a future + * version will support a flag that queries the cpu usage from the + * guest's perspective, using the number of vcpus available to the + * guest, found by virDomainGetVcpusFlags(). An individual guest + * vcpu cannot be reliably mapped back to a specific host cpu unless + * a single-processor vcpu pinning was used, but when @start_cpu is -1, + * any difference in usage between a host and guest perspective would + * serve as a measure of hypervisor overhead. + * + * Returns -1 on failure, or the number of statistics that were + * populated per cpu on success (this will be less than the total + * number of populated @params, unless @ncpus was 1; and may be + * less than @nparams). The populated parameters start at each + * stride of @nparams; any unpopulated parameters will be zeroed + * on success. The caller is responsible for freeing any returned + * string parameters. + * + * Note: + * Because cpu ids may be discontig, retuned @param array may contain + * zero-filled entry in the middle. + * All time related values are represented in ns, using UULONG. + * + * Typical use sequence is below. + * + * getting total stats: set start_cpu as -1, ncpus 1 + * virDomainGetCPUStats(dom, NULL, 0, -1, 1, 0) => nparams + * VIR_ALLOC_N(params, nparams) + * virDomainGetCPUStats(dom, parasm, nparams, -1, 1, 0) => total stats. + * + * getting percpu stats: + * virDomainGetCPUStats(dom, NULL, 0, 0, 0, 0) => max_cpu_id + * virDomainGetCPUStats(dom, NULL, 0, 0, 1, 0) => nparams + * VIR_ALLOC_N(params, max_cpu_id * nparams) + * virDomainGetCPUStats(dom, params, nparams, 0, max_cpu_id, 0) => percpu stats + * + */ + +int virDomainGetCPUStats(virDomainPtr domain, + virTypedParameterPtr params, + unsigned int nparams, + int start_cpu, + unsigned int ncpus, + unsigned int flags) +{ + virConnectPtr conn; + + VIR_DOMAIN_DEBUG(domain, "nparams=%d, start_cpu=%d, ncpu=%d, flags=%x", + nparams, start_cpu, ncpus, flags); + virResetLastError(); + + if (!VIR_IS_CONNECTED_DOMAIN(domain)) { + virLibDomainError(VIR_ERR_INVALID_DOMAIN, __FUNCTION__); + virDispatchError(NULL); + return -1; + } + + conn = domain->conn; + /* start_cpu == -1 is a special case. ncpus must be 1 */ + if ((start_cpu == -1) && (ncpus != 1)) { + virLibDomainError(VIR_ERR_INVALID_ARG, __FUNCTION__); + goto error; + } + /* if params == NULL, nparams must be 0 */ + if ((params == NULL) && ((nparams != 0))) { + virLibDomainError(VIR_ERR_INVALID_ARG, __FUNCTION__); + goto error; + } + + /* remote protocol doesn't welcome big args in one shot */ + if ((nparams > 16) || (ncpus > 128)) { + virLibDomainError(VIR_ERR_INVALID_ARG, __FUNCTION__); + goto error; + } + + if (conn->driver->domainGetCPUStats) { + int ret; + + ret = conn->driver->domainGetCPUStats(domain, params, nparams, + start_cpu, ncpus, flags); + if (ret < 0) + goto error; + return ret; + } + + virLibDomainError(VIR_ERR_NO_SUPPORT, __FUNCTION__); + +error: + virDispatchError(domain->conn); + return -1; +} diff --git a/src/libvirt_public.syms b/src/libvirt_public.syms index 1340b0c..7f9c5ab 100644 --- a/src/libvirt_public.syms +++ b/src/libvirt_public.syms @@ -520,6 +520,7 @@ LIBVIRT_0.9.10 { global: virDomainShutdownFlags; virStorageVolWipePattern; + virDomainGetCPUStats; } LIBVIRT_0.9.9; # .... define new API here using predicted next version number .... -- 1.7.4.1 -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list