[TriLUG] Memory Monitor on a Redhat system

[Kevin Kreamer]

Tom Le wrote:
> Sorry...I've been so busy with other stuff and have not had time to
> work on this ... anyway, this is from /proc/meminfo
> 
> # cat /proc/meminfo
> MemTotal:     16053064 kB
> MemFree:         50312 kB
> Buffers:        361476 kB
> Cached:       11939288 kB
> SwapCached:       7900 kB
> Active:        9351852 kB
> Inactive:      6222640 kB
> HighTotal:           0 kB
> HighFree:            0 kB
> LowTotal:     16053064 kB
> LowFree:         50312 kB
> SwapTotal:    10485720 kB
> SwapFree:     10212028 kB
> Dirty:             464 kB
> Writeback:           0 kB
> Mapped:        4968184 kB
> Slab:           392296 kB
> Committed_AS: 13508612 kB
> PageTables:     151168 kB
> VmallocTotal: 2147483647 kB
> VmallocUsed:      9376 kB
> VmallocChunk: 2147472663 kB
> HugePages_Total:     0
> HugePages_Free:      0
> Hugepagesize:    16384 kB
> 
> actual used memory = 3.5 G
>
> jboss did not give any error message - it would just not start and I
> think it's because of (out-of) memory problem.
> 
> This is the options for jvm: "-server -Xverify:none -Xms1024m -Xmx2560m"
> jboss is probably caching all the memory; and if that is the case,
> would anyone suggest how to flush the cache?
> The machine is 64-bit and we are running IBM jdk 1.5 for ppc64

It looks like most of your memory is just kernel caching, for which the
kernel only uses memory that is not otherwise needed.  It always caches
   about as much memory as you have left over. (the theory being: why
let the memory just sit there when you can have it speeding up your
system)  I think you might have a different problem than running out of
memory.

When you said that jboss didn't give any error message, are you
referring to errors from the logs or on the command line?  If the
command line, check to see if you got any error messages in your logs.
(check under /var/log)

Kevin

> On 3/29/07, Robert Dale <robdale at gmail.com> wrote:
>> On 3/29/07, Tom Le <t.thanhcle at gmail.com> wrote:
>> > We are having problems with memory usage on a Redhat AS 4 - on a
>> > 64-bit Power PC IBM pSeries. We was wondering if there is a reliable
>> > package to monitor memory usage on the server. Our current problem is
>> > that the system memory is 95% capacity and we have no idea what is
>> > taking up all the memory. We are certain that oracle is using 1G out
>> > of 16G of the box, and one instance of jboss is set to use max 1G of
>> > memory. We are trying to add a second instance of jboss and it won't
>> > start due to insufficient memory. We need a package or a way to drill
>> > down to what application using how much memory on the server
>> > Any suggestion is appreciated.
>>
>> When you say at 95% capacity is that including buffers and cache?
>>
>> What's your actual memory usage?  (/proc/meminfo would be useful here)
>> MemTotal - MemFree - Buffers - Cached = actual used memory
>>
>> What's the actual jboss error message?  Do you have the jvm stacktrace?
>> What jvm are you using?  What jvm options are you starting jboss with?
>>
>> -- 
>> Robert Dale
>> -- 
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