Re: [libvirt] [PATCH 1/1] virsh nodecpustats erroneously returns stats for offline cpus on Linux

On 12/19/2013 12:40 PM, Pradipta Kr. Banerjee wrote: > From: "Pradipta Kr. Banerjee" <bpradip(a)in.ibm.com&gt; > > virsh nodecpustats erroneously returns stats for offline cpus on Linux > > To retrieve node cpu statistics on Linux system, the > linuxNodeGetCPUstats function performs a minimal match of the input > cpuid with the cpuid read from /proc/cpustat. On systems with larger > cpus this can result in erroneous data. > For eg if /proc/stat has similar data > cpu 3645648 485 361475 3691194868 176595 40645 69850 0 1526172 0 > cpu0 494045 62 42763 138516619 16107 2339 2431 0 248345 0 > cpu4 402646 59 34745 138617562 17738 1413 1196 0 193948 0 > cpu8 318662 32 32119 138715131 7903 927 982 0 115429 0 > cpu12 247004 33 30465 138791438 5251 759 913 0 51938 0 > > and cpu 1,2 are offline, then > > 'virsh nodecpustats 1' displays data for cpu12 > > whereas virsh nodecpustats 2 correctly throws the following error > > "error: Unable to get node cpu stats > error: Invalid cpuNum in linuxNodeGetCPUStats" > > This patch fixes the above mentioned problem > > Signed-off-by: Pradipta Kr. Banerjee <bpradip(a)in.ibm.com&gt; > --- > src/nodeinfo.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/src/nodeinfo.c b/src/nodeinfo.c > index 1838547..c9e5ff1 100644 > --- a/src/nodeinfo.c > +++ b/src/nodeinfo.c > @@ -614,6 +614,8 @@ linuxNodeGetCPUStats(FILE *procstat, > unsigned long long usr, ni, sys, idle, iowait; > unsigned long long irq, softirq, steal, guest, guest_nice; > char cpu_header[3 + INT_BUFSIZE_BOUND(cpuNum)]; > + char cpu_header_read[3 + INT_BUFSIZE_BOUND(cpuNum)]; > + char cpu_header_fmt[8]; > > if ((*nparams) == 0) { > /* Current number of cpu stats supported by linux */ > @@ -631,8 +633,11 @@ linuxNodeGetCPUStats(FILE *procstat, > > if (cpuNum == VIR_NODE_CPU_STATS_ALL_CPUS) { > strcpy(cpu_header, "cpu"); > + snprintf(cpu_header_fmt, sizeof(cpu_header_fmt), "%%%ds", 3); > } else { > snprintf(cpu_header, sizeof(cpu_header), "cpu%d", cpuNum); > + snprintf(cpu_header_fmt, sizeof(cpu_header_fmt), "%%%ds", > + (int)(3 + INT_BUFSIZE_BOUND(cpuNum))); > } > > while (fgets(line, sizeof(line), procstat) != NULL) { > @@ -649,6 +654,14 @@ linuxNodeGetCPUStats(FILE *procstat, > continue; > } > > + /* > + * Process with stats gathering only if the cpuid from /proc/stat > + * matches exactly with the input cpuid > + */ > + sscanf(buf, cpu_header_fmt, cpu_header_read); > + if (STRNEQ(cpu_header, cpu_header_read)) > + continue; > + > for (i = 0; i < *nparams; i++) { > virNodeCPUStatsPtr param = &params[i]; What about this? diff --git a/src/nodeinfo.c b/src/nodeinfo.c index 1838547..aa1ad81 100644 --- a/src/nodeinfo.c +++ b/src/nodeinfo.c @@ -637,8 +637,9 @@ linuxNodeGetCPUStats(FILE *procstat, while (fgets(line, sizeof(line), procstat) != NULL) { char *buf = line; + char **buf_header = virStringSplit(buf, " ", 2); - if (STRPREFIX(buf, cpu_header)) { /* aka logical CPU time */ + if (STREQ(buf_header[0], cpu_header)) { /* aka logical CPU time */ size_t i; if (sscanf(buf, @@ -697,6 +698,7 @@ linuxNodeGetCPUStats(FILE *procstat, ret = 0; goto cleanup; } + virStringFreeList(buf_header); } virReportInvalidArg(cpuNum,

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