Re: [libvirt] [PATCHv6 0/6] Add virNodeGetCPUStats() API
On Wed, May 25, 2011 at 03:01:29PM +0900, Minoru Usui wrote:
Hi,
This is v6 of virNodeGetCPUTimeParameters() API.
(This time, I rename it to virNodeGetCPUStats())
It returns cpu utilization or
cumulative cpu time of the node from /proc/stat since node boots up.
This patch only supports linux host.
The code in this patch series looks fine to me now. I would
ACK the whole series, but I have one design question I should
have asked previously.
This API returns CPU information for the host as a whole.
Historically, when adding an API like this, someone has always
then asked for a per-CPU breakdown of the same data.
So I wonder if we should add a parameter for the CPU num
to the API:
int virNodeGetCPUStats (virConnectPtr conn,
int cpuNum,
virCPUStatsPtr params,
int *nparams,
unsigned int flags);
And have a constant for getting the host data as a whole:
#define VIR_NODE_CPU_STATS_ALL_CPUS -1
so if you want to get individual data for each CPU you
can do
virNodeGetCPUStats(conn, 0, params, nparams, flags);
virNodeGetCPUStats(conn, 1, params, nparams, flags);
virNodeGetCPUStats(conn, 2, params, nparams, flags);
virNodeGetCPUStats(conn, 3, params, nparams, flags);
But if you just want the data for the host as a whole
you can do
virNodeGetCPUStats(conn, VIR_NODE_CPU_STATS_ALL_CPUS,
params, nparams, flags);
The /proc/stat file already has the data we need for both
these styles
$ grep cpu /proc/stat
cpu 2632143 17400 1341532 32819705 1177560 674 21606 0 11997 0
cpu0 1263069 9280 596278 16274365 620428 631 17303 0 6131 0
cpu1 1369073 8119 745254 16545339 557131 43 4302 0 5865 0
Regards,
Daniel
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