memory 被用光了

[watermelonyu]

最近系統在做測試, 用 glance 看發現 memory 都被用光, 之後 CPU loading 飆到 15x ... 看了一下發現是一隻程式 vhand 在使用 CPU, 請教除了加 memory, 還有可能是什麼問題呢 ?



Physical : 4G

Swap : 8G

跑了四個 JVM

[watermelonyu]

簡單的說, 當系統memory不足時, vhand就會起來, 處理page-in/page-out



以下為相關的技術智識庫文章編號, 先看看, 如有問題再發問 :-)

A4751703

UNX1000267

DY028578

UCMDSKBRC00007173

RPMMWKBRC00006978

KBRC00014838



http://www.itrc.hp.com/service/cki/enterService.do

[watermelonyu]

The kernel always tried to maintain a threshold

of free pages in order to keep the system

running efficiently. As long as this threshold,

referred to as lotsfree, is maintained, no

pagine occurs. When the number of free pages

drops below this threshold, a deamon know as

vhand selects pages that haven't been recently

referenced, copies them out to swap, then adds

the pages to the free page list. This is

referred to as a page-out. A page fault occurs

when a process tries to access a page that is

not currently in memory. The page will then be

copied into RAM via a page-in, either from the

swap space or from the executable on disk.



On systems with very demanding memory needs(for

example, systems that run many large processes,

such as JVM), the paging daemons can become so

busy swapping pages in and out, that the system

spends all of it's time paging, and not enough

time running process. When this happens, system

performance degrades rapidly. At this point,

the system is said to be thrashing. If vhand is

consuming a large amount of CPU time, consider

purchasing more physical memory.

[watermelonyu]

1. High sustained page _out_ rates (paging in is normal) (vmstat 5 30)。

2. Small number of free and active virtual memory pages (vmstat 5 30)。

High disk activity on swap devices (sar -d, glance, iostat)。

3. Out of memory errors。

4. CPU time given to vhand (and swapper at 9.X) (ps -ef, top, glance)。

5. Excessive CPU time given to system versus user processes。

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Can you post the output for above commands?

[watermelonyu]

Pls refer ... 技術智識庫,文件 ID: KBRC00014838