One of the most common mistakes made by Linux users, is to run free (Mem: line) or sar to get memory utilization. The memory used fields include the space used by the OS to cache files and directory info cace,…
Tag: performance
Sar Grapher Updated
Sar Grapher has been updated. It now graphs Linux NFS Server performance data.
Sun/Oracle Java Default Values
/opt/java/jdk1.6.0_21/bin/java -XX:+PrintFlagsFinal -version [Global flags] uintx AdaptivePermSizeWeight = 20 {product} uintx AdaptiveSizeDecrementScaleFactor = 4 {product} uintx AdaptiveSizeMajorGCDecayTimeScale = 10 {product} uintx AdaptiveSizePausePolicy = 0 {product} uintx AdaptiveSizePolicyCollectionCostMargin = 50 {product} uintx AdaptiveSizePolicyInitializingSteps = 20 {product} uintx AdaptiveSizePolicyOutputInterval = 0 {product}…
Getting JVM config
Use jmap to get a running JVM configuration For example: <path2java>/bin/jmap -heap <pid> JVM version is 17.0-b16 using parallel threads in the new generation. using thread-local object allocation. Concurrent Mark-Sweep GC Heap Configuration: MinHeapFreeRatio = 40 MaxHeapFreeRatio =…
Sargrapher Now Graphs Total CPU time
Sar grapher now displays graphs of total CPU time used. This makes it more obvious of combination of user, system, I/O wait.
Increasing Linux Ring Buffer Size
This doesn’t work on all drivers, but on the bnx2x and other it does. In particular, if you are seeing packet drops this can help. Use ethtool –g <interface> to see the buffer settings. # ethtool -g eth0 Ring…