Hi, Terry: I am trying to give out the real number, I won't try to fool your guys and waste your time. We are running Sun Fire V880, with 8*1.2G CPu and 16G memory, and a HDS9570 15*73GB Raid10 storage. The following is the IO statistics from unix(iostat -xnz 2) extended device statistics r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device 0.5 0.0 4.0 0.0 0.0 0.0 0.0 0.7 0 0 c1t0d0 296.5 0.5 7364.2 4.0 0.0 1.1 0.0 3.6 0 71 c3t50060E8000439AA0d2 171.5 55.0 1372.0 1346.8 0.0 0.9 0.0 3.8 0 66 c3t50060E8000439AA0d1 We did not setup the storage with optimal setting, which according to HDS engineer, should be setup as 3* (2D+2P) raid group + 2standby. While we setup it like (6D+6P)+2 standby . ----- Original Message ----- From: Terry Sutton To: oracle-l@xxxxxxxxxxxxx Sent: Wednesday, June 09, 2004 11:35 PM Subject: Re: see higher CPU usage after increase SGA Your data doesn't seem to make sense. You say that your disk hits 75% busy, but you're only doing 448 physical I/Os per second. On a system your size I don't see how that level of PIOs would keep a disk that busy. --Terry > Hi, > I did not post the all information within that email, else it will be > too lenghy, and few people will read it through. > 1. There is no pagein/out taking place. Vmstat shows sr=0 and sar -g > shows no swapin/out. > 2. At this time, neither CPU nor Disk is not bottleneck now. We can > support more users. Disk is reaching its capacity soon, as > BUSY%(iostat -xn ) is at 75%+ during peak time. This is why we increase SGA > to reduce the load on disk storage. > 3. You said it can because larger sga caused scanning the LATCH using > more CPU. I also think it is possible. But difficult to verify. > 4.It is difficult to find out who used more resource. As there are 800+ > connection to the database, using the same username. And I did not record > the old v$sesstat. Even record that old v$sesstat, it is difficult to > compare that 5% in the 800+ sessions. > > It is just I am not sure what caused the more CPU usage. Hotsos notes > cannot explain everything, I read most of the notes there more than 5 times. > One of them is LIO consumes much CPU, which I do not quite agree, according > to my tune experience in the past several weeks. > There was a HUGE SQL(which used 30% of total system buffer_gets > according to statspack report). I changed the SQL, and later it used less > than 0.5% of total system buffer_gets(it just dissappear from statspack > report), but system CPU usage just drop by less than 5% from statspack > report(compare the CPU used by this session before/after change)!. > > Regards > Zhu Chao. > > > ----- Original Message ----- > From: "Mark W. Farnham" <mwf@xxxxxxxx> > To: <oracle-l@xxxxxxxxxxxxx> > Sent: Wednesday, June 09, 2004 10:03 PM > Subject: RE: see higher CPU usage after increase SGA > > > > Now, trying to be actually useful, I think your next task is to find out > > where time is being spent. If analysis shows that the big consumer(s) > is/are > > already doing as little work as possible, then you make the restrictive > > system component faster (or discover that it is not cost effective to make > > the bottleneck resource faster.) If analysis shows that big consumer(s) > > is/are doing more work than required for the task at hand, you work to > > improve the big consumer(s). > > > > mwf > > > > -----Original Message----- > > From: oracle-l-bounce@xxxxxxxxxxxxx > [mailto:oracle-l-bounce@xxxxxxxxxxxxx]On > > Behalf Of zhu chao > > Sent: Wednesday, June 09, 2004 9:31 AM > > To: oracle-l@xxxxxxxxxxxxx > > Subject: see higher CPU usage after increase SGA > > > > > > Hi, > > I once saw Jonathan said at metalink that huge SGA does not help in > many > > case, But no further discuss at that topic later. Last night we added 1Gb > > to oracle sga and we see fewer disk read but higher CPU usage. > > > > Fewer disk read of course cut CPU usage, but larger buffer cache > > management in unix and oracle, seems caused higher CPU usage. Has someone > > also have similar experience? How to explain the higher CPU usage? > > > > We have a 16GB memory sun 880 with 10G data cache. As disk read get > > higher and higher , and not much SQL to tune we deciede to increase data > > buffer from 10G to 11GB, as there is still 1.5G free memory on the host. > > > > We expect to see some CPU usage drop, as disk read drop by 30%. But > > after 1 day's run, we saw higher CPU usage then before we increase the > SGA. > > > > http://www.cnoug.org/attachments/LDBn_cpu.bmp (the Excel picture that > > shows the CPU usage before and after increase sga). > > The following Statistics from Oracle shows the load profile before and > > after SGA increase: > > > > LIO PIO Transaction/Second > > CPU usage in oracle > > 10gb 47,990.70 448.68 76.54 > > 177.9 > > 11gb 47,707.28 325.95 76.54 > > 187.9 > > Change: Nearly same Disk read dropped Transaction > rate > > CPU used increased. > > 30% keep > consistent > > by 5% > > > > > > Time I measure: 9 am ? 15pm. > > Oracle: 5% increase. > > Unix: 6% increase. > > > > > > ---------------------------------------------------------------- > > Please see the official ORACLE-L FAQ: http://www.orafaq.com > > ---------------------------------------------------------------- > > To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx > > put 'unsubscribe' in the subject line. > > -- > > Archives are at //www.freelists.org/archives/oracle-l/ > > FAQ is at //www.freelists.org/help/fom-serve/cache/1.html > > ----------------------------------------------------------------- > > > > > > ---------------------------------------------------------------- > > Please see the official ORACLE-L FAQ: http://www.orafaq.com > > ---------------------------------------------------------------- > > To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx > > put 'unsubscribe' in the subject line. > > -- > > Archives are at //www.freelists.org/archives/oracle-l/ > > FAQ is at //www.freelists.org/help/fom-serve/cache/1.html > > ----------------------------------------------------------------- > > > > > > ---------------------------------------------------------------- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > ---------------------------------------------------------------- > To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx > put 'unsubscribe' in the subject line. > -- > Archives are at //www.freelists.org/archives/oracle-l/ > FAQ is at //www.freelists.org/help/fom-serve/cache/1.html > ----------------------------------------------------------------- > >