Yunqi Zhang created HADOOP-12356:
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Summary: CPU usage statistics on Windows
Key: HADOOP-12356
URL: https://issues.apache.org/jira/browse/HADOOP-12356
Project: Hadoop Common
Issue Type: Bug
Components: util
Environment: CPU: Intel Xeon
OS: Windows server
Reporter: Yunqi Zhang
In {{hadoop-common/src/main/java/org/apache/hadoop/util/SysInfoWindows.java}}
(in trunk), the reported CPU usage is incorrect.
{code:title=SysInfoWindows.java|borderStyle=solid}
// This is where we calculate all the usage information
void refreshIfNeeded() {
...
if (lastCumCpuTimeMs != -1) {
cpuUsage = (cumulativeCpuTimeMs - lastCumCpuTimeMs)
/ (refreshInterval * 1.0f);
}
...
}
{code}
This {{cpuUsage}} is the cumulative CPU usage across all logical cores. For
example, this number will range in [0.0, 12.0] if a server has 12 cores.
Instead of reporting this raw number, we should do the following to be
consistent with {{SysInfoLinux.java}}. In {{SysInfoLinux.java}}, {{cpuUsage}}
ranges in [0.0, 1200.0], and the return value of {{getCpuUsage()}} ranges from
[0.0, 100.0].
{code:title=SysInfoWindows.java|borderStyle=solid}
// This is where we calculate all the usage information
void refreshIfNeeded() {
...
if (lastCumCpuTimeMs != -1) {
cpuUsage = (cumulativeCpuTimeMs - lastCumCpuTimeMs)
* 100F / refreshInterval;
}
...
}
@Override
public float getCpuUsage() {
refreshIfNeeded();
return cpuUsage / numProcessors;
}
{code}
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