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Home -> Community -> Mailing Lists -> Oracle-L -> Re: memory usage by dbw very high
hi tanel and mladen
not every time a process is started does it swap but sometimes swapping does happen.(this is from the top o/p which shows a increase in the memory used in swap.).how do we check whether a single process swaps or not?
and the dbw process is using more % of memory than a couple of days back.(o/p pf ps aux). is this how linux kernel works or is there something else i can check.
thanks
sai
what is meant by OP,tanel..
Tanel Poder <tanel.poder.003_at_mail.ee> wrote: Thanks Mladen, that was a good tip about linux kernel enhancement, however OP still uses 2.4.9 as stated in original post.
I just wanted to know whether OP actually sees excessive paging or just memory being "full", the latter one, as you know, isn't really a problem.
Tanel.
> The whole thing comes as a consequence of using buffered I/O. New linux
> kernels (2.4.18 and later) have new memory management, which allows
> the kernel to grab more memory for buffers in periods of intense I./O
> activity. If you have a very active database on ReiserFS or Ext3, Linux is
> going to try to help you out by allocating more memory for the file system
> buffers, even by stealing pages from the active processes, which will, in
> turn. start paging. The only possible response is to eliminate the
buffered I/
> O and switch to non-buffered I/O. That is not so hard to do.
>
> On 2003.11.01 09:44, Tanel Poder wrote:
> > Just for clarification, do you actually see swapping when starting a new
> > process or you just guess linux would swap because you don't see "free"
> > memory in top output?
> >
> > Tanel.
> >
> > ----- Original Message -----
> > From: Sai Selvaganesan
> > To: Multiple recipients of list ORACLE-L
> > Sent: Saturday, November 01, 2003 1:34 AM
> > Subject: RE: memory usage by dbw very high
> >
> >
> > rich
> > the ipcs output shows 1.1 gb. so nearly 2 gb(total ram size is 3.08)
is
> > used by non shared memory size.
> > i went thru all the processes and found dbwr using the max %mem. what
> > could
> > be the reason?
> > sai
> >
> > "Jesse, Rich" wrote:
> > If I'm not mistaken, this figure includes the size of the shared
memory
> > segment from the SGA. Take the output of the "oracle" line of
"ipcs -a"
> > (hopefully you'll only have one!) and subtract it from the process
size
> > to
> > get a better idea of the non-shared memory size of the process.
> >
> > Rich
> >
> > Rich Jesse System/Database Administrator
> > rjesse_at_qtiworld.com Quad/Tech Inc, Sussex, WI USA
> >
> >
> > -----Original Message-----
> > Sent: Friday, October 31, 2003 3:49 PM
> > To: Multiple recipients of list ORACLE-L
> >
> >
> > hi
> >
> > i have a system that has no active users at this point of time. the
> > memory
> > used by the dbw process is very high leading to a lot of swapping
when
> > any
> > process starts.
> > here are the spces
> > version:9.2.0.4
> > os:Linux 2.4.9-e.24smp
> > o/p from top:
> > 1:44pm up 29 days, 23:55, 4 users, load average: 1.73, 1.68, 1.35
> > 132 proces! ses: 131 sleeping, 1 running, 0 zombie, 0 stopped
> > CPU0 states: 24.4% user, 2.2% system, 0.0% nice, 72.2% idle
> > CPU1 states: 0.5% user, 0.5% system, 0.0% nice, 98.0% idle
> > CPU2 states: 0.0% user, 0.1% system, 0.0% nice, 99.4% idle
> > CPU3 states: 0.3% user, 0.4% system, 0.0% nice, 98.3% idle
> > Mem: 3089964K av, 3083380K used, 6584K free, 846848K shrd, 193448K
> > buff
> > Swap: 2048152K av, 1652K used, 2046500K free 1852468K
> > cached
> > sga size:
> > Total System Global Area 1084823632 bytes
> > Fixed Size 452688 bytes
> > Variable Size 335544320 bytes
> > Database Buffers 738197504 bytes
> > Redo Buffers 10629120 bytes
> > pga aggregate size:700M
> > and ps o/p of dbw process
> > USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
> > oracle 4062 0.0 16.4 1131260 508168 ? S 10:16 0:06
> > ora_dbw0_revenue
> >
> > please advise. what is really going on.
> >
> > thanks
> > sai
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > --
> > Author: Jesse, Rich
> > INET: Rich.Jesse_at_qtiworld.com
> >
> > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > San Diego, California -- Mailing list and web hosting services
>
-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Tanel Poder INET: tanel.poder.003_at_mail.ee Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Sai Selvaganesan INET: ssaisundar_at_sbcglobal.net Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Mon Nov 03 2003 - 12:24:27 CST
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