Re: FSI TX200 S2 and main memory > 4 GB
Tom Sightler <[email protected]>
| Newsgroups | gmane.linux.suse.oracle.general |
|---|---|
| Message-ID | <[email protected]> |
On Thu, 2007-06-21 at 09:29 -0300, [email protected] wrote: > > Oh, Interesting !! > > I have the same configuration (64bit and 16GB RAM), the script from > metalink note 401749.1recommend me: > > lnrsdb0:~ # ./hugepages_settings.sh > Recommended setting: vm.nr_hugepages = 3996 > > And my SGA is: > > SQL> show sga > > Total System Global Area 4414479016 bytes > Fixed Size 748200 bytes > Variable Size 738197504 bytes > Database Buffers 3674210304 bytes > Redo Buffers 1323008 bytes > Well, assuming SuSE uses 2048MB Hugepages (I'm mostly a Redhat person, sorry) then 3996 huge pages is reasonably close to 8GB, but you only have a 4.5GB SGA. That means that 3.5GB of your RAM is likely going to waste right now. When you allocate hugepages, the system reserves them immediately and that memory can only be used by programs which specifically requrest hugepage memory. You can verify this by running "cat /proc/meminfo" and looking at the last few lines which show your "hugepages" allocation. My guess is you'll se something like: HugePages_Total: 3996 HugePages_Free: 1891 Hugepagesize: 2048 kB If so, that would mean that Oracle is using 2105 hugepages and the other 1891 (about 3.6GB) are basically going to waste. If you have memory going to waste then this is one of the places where huge pages can work against you. If it turns out that you have huge pages going to waste you should either increase your SGA to allow Oracle to use them, or decrease your allocation of huge pages to the kernel so that it can use the memory for other things. The above is just a guess based on the information you've provided, feel free to post the actual HugePages numbers so that we can know for sure. Later, Tom -- To unsubscribe, email: [email protected] For additional commands, email: [email protected] Please see http://www.suse.com/oracle/ before posting