Re: MEMORY leakage
- From: Tim Gorman <tim@xxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 09 Sep 2004 18:35:43 -0600
Dinesh,
Most likely, it is the UNIX buffer cache (UBC) for the file-systems which i=
s
making the "free" memory statistic appear low (and suspiciously constant).
Typically, the UBC is configured to utilize all but a small percentage of
memory if it needs it, but it is also designed to "give up" that memory upo=
n
request when it is needed for another purpose. Memory needed for process
images are "stolen" from the UBC before the "free" memory is tapped into,
resulting in a consistent low amount of memory marked "free" regardless of
activity on the system.
I have seen reports from HPUX which break out UBC usage from process images
using the HP "perfview" tool. I don't know if you can get a similar report
(i.e. UBC, RSS, etc) from Solaris. Anybody? Anybody? Bueller? Bueller?
Anybody?
In other words, what you are seeing most likely is not a problem, simply a
misinterpretation (an understandable one) of the meaning of the statistics.
To determine if this is indeed the case, what do you think the likelihood i=
s
that "free" memory would remain at 46Mb consistently, regardless of stuff
starting and finishing, spawning and exiting? Is that what you are seeing,
or are you seeing that figure fluctuate?
Also, have you seen "page in" activity (i.e. paged out blocks being
retrieved back into resident memory)? Since there is usually constant
proactive "page out" activity at all times, "page in" activity typically
indicates pressure on the memory resource. If you're not seeing constant
"page in" activity, then the whole issue is moot anyway.
Also, check to see if the "fsflush" process is very busy -- that also tends
to indicate lots of UBC activity, as "fsflush" is UNIX's corollary to
Oracle's DBWR process. A busy "fsflush" process isn't necessarily a bad
thing, it just helps explain the situation.
Hope this helps...
-Tim
on 9/8/04 9:05 PM, Seema Singh at oracledbam@xxxxxxxxxxx wrote:
> Hi,
> When I rebooted the Solaris box the memory was free 1130mb out 1536mb(tot=
al
> physical memory).After 2 hrs ONLY 46mb memory is free.All oracle processe=
s
> are eating 253mb around.Wondering how to fix it?
> Is it Solaris level problem? Solaris 5.7 and 817.0.0 are running.
> thanks
> -Dinesh
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