[libvirt] [PATCHv2 10/11] qemu: bulk stats: implement block group
Eric Blake
eblake at redhat.com
Tue Sep 2 23:10:37 UTC 2014
On 09/02/2014 06:31 AM, Francesco Romani wrote:
> This patch implements the VIR_DOMAIN_STATS_BLOCK
> group of statistics.
>
> Signed-off-by: Francesco Romani <fromani at redhat.com>
> ---
> include/libvirt/libvirt.h.in | 1 +
> src/libvirt.c | 13 +++++++++
> src/qemu/qemu_driver.c | 65 ++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 79 insertions(+)
>
> diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
> index 33588d6..1d90f5e 100644
> --- a/include/libvirt/libvirt.h.in
> +++ b/include/libvirt/libvirt.h.in
> @@ -2515,6 +2515,7 @@ typedef enum {
> VIR_DOMAIN_STATS_BALLOON = (1 << 2), /* return domain balloon info */
> VIR_DOMAIN_STATS_VCPU = (1 << 3), /* return domain virtual CPU info */
> VIR_DOMAIN_STATS_INTERFACE = (1 << 4), /* return domain interfaces info */
> + VIR_DOMAIN_STATS_BLOCK = (1 << 5), /* return domain block info */
> } virDomainStatsTypes;
>
> typedef enum {
> diff --git a/src/libvirt.c b/src/libvirt.c
> index 099404b..cabfb91 100644
> --- a/src/libvirt.c
> +++ b/src/libvirt.c
> @@ -21579,6 +21579,19 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
> * "net.<num>.tx.errs" - transmission errors.
> * "net.<num>.tx.drop" - transmit packets dropped.
> *
> + * VIR_DOMAIN_STATS_BLOCK: Return block devices statistics.
> + * The typed paramer keys are in this format:
s/paramer/parameter/
> + * "block.count" - number of block devices on this domain.
> + * "block.<num>.name" - name of the block device <num>.
Does this match up to the <target dev='vda'/> name?
> + * "block.<num>.rd.reqs" - number of read requests.
> + * "block.<num>.rd.bytes" - number of read bytes.
> + * "block.<num>.rd.times" - total time (ns) spent on reads.
> + * "block.<num>.wr.reqs" - number of write requests
> + * "block.<num>.wr.bytes" - number of written bytes.
> + * "block.<num>.wr.times" - total time (ns) spent on writes.
> + * "block.<num>.fl.reqs" - total flush requests
> + * "block.<num>.fl.times" - total time (ns) spent on cache flushing
Missing types. Inconsistent on whether you use a trailing '.'
Just because qemu doesn't report a meaningful errs does not mean that
the public API should omit it. Hypervisors need only return the subset
of typed parameters that make sense, but we ought to document a typed
parameter for all possible fields for the API calls that this is copying
from.
> + *
> * Using 0 for @stats returns all stats groups supported by the given
> * hypervisor.
> *
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 069a15d..977e8c7 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -17542,6 +17542,70 @@ qemuDomainGetStatsInterface(virConnectPtr conn ATTRIBUTE_UNUSED,
>
> #undef QEMU_ADD_NET_PARAM
>
> +#define QEMU_ADD_BLOCK_PARAM_LL(RECORD, MAXPARAMS, NUM, NAME, VALUE) \
> +do { \
> + char param_name[NAME_MAX]; \
Oversized.
> +static int
> +qemuDomainGetStatsBlock(virConnectPtr conn ATTRIBUTE_UNUSED,
> + virDomainObjPtr dom,
> + virDomainStatsRecordPtr record,
> + int *maxparams,
> + unsigned int privflags ATTRIBUTE_UNUSED)
> +{
> + size_t i;
> + int ret = -1;
> + int nstats = dom->def->ndisks;
ndisks may include such things as a cdrom drive with no media...
> + struct qemuBlockStats *stats = NULL;
> + virQEMUDriverPtr driver = conn->privateData;
> +
> + if (VIR_ALLOC_N(stats, nstats) < 0)
> + return -1;
> +
> + if (qemuDomainGetBlockStats(driver, dom, stats, nstats) != nstats)
...so it is possible that nstats might be less than ndisks. Is that
really a reason to return failure, instead of at least reporting the
information that was available?
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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