Re: What is using the memory

On 28/06/07, George Thompson <george@xxxxxxx> wrote:
> On 26/06/07, George Thompson <george@xxxxxxx> wrote:
>> Running RHEL4
>>
>> We are uing weblogic which has three java proceses. The sum of the
>> percentage memory used of these processes is about 42% .
>>
>> ps -aux | grep java | gawk '{ print $11, $4}'
>> /opt/od-home/OpenDeployNG/jre/bin/java 0.3
>> /opt/java/liveJava/bin/java 24.2
>> /opt/java/liveJava/bin/java 18.1
>>
>>
>> If I do ps -aux and add up all the %cpu coulums it totals about 45%. Yet
>> when i look at sar -r
>>
>> sar -r | gawk '{ print $1, $2, $5}' | head
>> 12:00:01 AM %memused
>> 12:10:01 AM 99.76
>> 12:20:01 AM 99.72
>>
>> It seems to think the memory is 99% used. But I cant see any other
>> processes in the process table using any significant memory.
>>
>> Here is the contents of /proc/meminfo . I dont fully understand what all
>> the entries mean.
>>
>> [root@web1]/etc# cat /proc/meminfo
>> MemTotal: 8164748 kB
>> MemFree: 164748 kB
>> Buffers: 108356 kB
>> Cached: 478412 kB
>> SwapCached: 38628 kB
>> Active: 3690740 kB
>> Inactive: 409064 kB
>> HighTotal: 0 kB
>> HighFree: 0 kB
>> LowTotal: 8164748 kB
>> LowFree: 164748 kB
>> SwapTotal: 16779884 kB
>> SwapFree: 16643592 kB
>> Dirty: 2508 kB
>> Writeback: 0 kB
>> Mapped: 3529560 kB
>> Slab: 185824 kB
>> CommitLimit: 20862256 kB
>> Committed_AS: 7658544 kB
>> PageTables: 13484 kB
>> VmallocTotal: 536870911 kB
>> VmallocUsed: 271300 kB
>> VmallocChunk: 536599035 kB
>> HugePages_Total: 0
>> HugePages_Free: 0
>> Hugepagesize: 2048 kB
>> [root@weblogic1]/etc#
>>
>> Our customer is asking us to explain what is using the memory and we
>> have
>> no answer.
>>
>> George
>
> If you'd like a more detailed explanation than Joseph's reply, check
> out http://gentoo-wiki.com/FAQ_Linux_Memory_Management or use your
> favorite web browser and search for "linux memory management".
>
> Kind regards,
>
> Herta
>


Thanks, in this case the big user of memory appears to be the "Mapped"
entry in meminfo. I have neither seen or read anything which explains the
rather large value !

G


Not sure if that helps you, but "Mapped" refers to devices, files, and
libraries which have been mmaped (memory mapped) into pagetables.
(Cf. http://en.wikipedia.org/wiki/Mmap)

Without knowing your application, it'd be hard to judge whether
3529560 kB out of 8164748 kB is reasonable or not.

Kind regards,

Herta

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