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