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linux_wiki:high_system_load [2015/12/08 08:58] billdozor [Traffic/Bridge analogy] |
linux_wiki:high_system_load [2016/03/14 11:32] billdozor |
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* 2 CPU/Cores = 100% is load 2.00 | * 2 CPU/Cores = 100% is load 2.00 | ||
* 4 CPU/Cores = 100% is load 4.00 | * 4 CPU/Cores = 100% is load 4.00 | ||
- | * Example: From the analogy above, each CPU Core can handle | + | * Example: From the analogy above, each CPU Core can actively process |
===== Calculate Overall CPU Load ===== | ===== Calculate Overall CPU Load ===== | ||
- | * Get number of CPUs | + | * Get number of CPUs< |
- | * <code bash> | + | OR |
+ | nproc</ | ||
* Load Average / NumProccessors = decimal % load | * Load Average / NumProccessors = decimal % load | ||
* Example: LoadAvg(1.5) / 2 Processors = 0.75 or 75% system load on a dual core system. | * Example: LoadAvg(1.5) / 2 Processors = 0.75 or 75% system load on a dual core system. | ||
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---- | ---- | ||
- | ==== High CPU ==== | + | ===== High CPU ===== |
Clues that you should investigate high CPU usage: | Clues that you should investigate high CPU usage: | ||
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---- | ---- | ||
- | ==== High Memory Use ==== | + | ===== High Memory Use ===== |
Notes on Linux memory management | Notes on Linux memory management | ||
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---- | ---- | ||
- | ==== Disk I/O ==== | + | ===== Disk I/O ===== |
* I/O wait (wa) is the percentage of time a CPU is waiting on disk. | * I/O wait (wa) is the percentage of time a CPU is waiting on disk. | ||
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* High CPU " | * High CPU " | ||
+ | \\ | ||
**iostat** - View I/O stats with extended statistics, every 3 seconds | **iostat** - View I/O stats with extended statistics, every 3 seconds | ||
<code bash> | <code bash> | ||
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* " | * " | ||
+ | \\ | ||
**iotop** - Live disk I/O similar to top | **iotop** - Live disk I/O similar to top | ||
<code bash> | <code bash> | ||
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</ | </ | ||
+ | \\ | ||
**lsof** - If a particular device is discovered, another option for further details is to list open files for that mount point. | **lsof** - If a particular device is discovered, another option for further details is to list open files for that mount point. | ||
* Device discovered via iostat | * Device discovered via iostat |