[GitHub] [cloudstack] weizhouapache commented on a change in pull request #5506: kvm: Use lscpu to get cpu max speed

[GitBox <gi...@apache.org>]

weizhouapache commented on a change in pull request #5506:
URL: https://github.com/apache/cloudstack/pull/5506#discussion_r715489059



##########
File path: plugins/hypervisors/kvm/src/main/java/org/apache/cloudstack/utils/linux/KVMHostInfo.java
##########
@@ -85,8 +87,18 @@ protected static long getCpuSpeed(final NodeInfo nodeInfo) {
             LOGGER.info(String.format("Retrieved value [%s] from file [%s]. This corresponds to a CPU speed of [%s] MHz.", cpuInfoMaxFreq, cpuInfoMaxFreqFileName, cpuInfoMaxFreq / 1000));
             return cpuInfoMaxFreq / 1000;
         } catch (IOException | NumberFormatException e) {
-            LOGGER.error(String.format("Unable to retrieve the CPU speed from file [%s]. Using the value [%s] provided by the Libvirt.", cpuInfoMaxFreqFileName, nodeInfo.mhz), e);
-            return nodeInfo.mhz;
+            try {
+                LOGGER.error(String.format("Unable to retrieve the CPU speed from file [%s]. Trying to fetch it from lscpu",
+                    cpuInfoMaxFreqFileName), e);
+                String command = "lscpu | grep -i 'Model name' | head -n 1 | egrep -o '[[:digit:]].[[:digit:]]+GHz' | sed 's/GHz//g'";

Review comment:
       @rhtyd @davidjumani 
   
   there are multiple ways to get the cpu speed. 
   
   while(true);do cat /proc/cpuinfo |grep 'cpu MHz' |head -n1;sleep 0.1;done
   while(true);do virsh nodeinfo |grep 'CPU frequency';sleep 0.1;done
   
   it looks the result by `lscpu` is most stable. I am not sure if it works for all cpu models.
   
   it seems we should not get cpu speed from `/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq`. If cpu supports Intel Turbo Boost Technology, it is the max cpu frequency not the normal cpu frequency.  for example, on my laptop
   ```
   $ cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
   4700000
   $ virsh nodeinfo |grep 'CPU frequency'
   CPU frequency:       2800 MHz
   $ cat /proc/cpuinfo |grep 'cpu MHz' |head -n1
   cpu MHz		: 2800.000
   ```
   
   my opinion is: lscpu > nodeInfo.mhz (libvirt-java) -> /proc/cpuinfo > cpuinfo_max_freq




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