What is using the memory

[Herta Van den Eynde]

On 28/06/07, George Thompson <george at twig.tk> wrote:
> > On 26/06/07, George Thompson <george at twig.tk> 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 at 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 at 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