Re: lock_sga error
- From: Tanel Põder <tanel.poder.003@xxxxxxx>
- To: "Oracle-L (E-mail)" <oracle-l@xxxxxxxxxxxxx>
- Date: Sat, 6 Aug 2005 00:23:39 +0100
Re: lock_sga errorHi, I'm not sure whether Linux supports shared pagetables (which Kevin already mentioned), that would help us to keep the kernel virtual<->physical memory pagetables smaller and hardware TLBs more efficient and since all processes would access locked parts of SGA using the same pagetable entries (as the virtual memory pages are known to remain in the same physical memory address), we might have less soft page faults, thus improved performance in servers having high number of server processes running in them. But I don't know whether Linux actually supports shared page tables. But anyway, if you run ulimit -l you should see what's the ulimit for max lockable memory for your user, you should set it to at least the size of SGA (or parts of the SGA) which you're gonna lock. Tanel. ----- Original Message ----- From: Tim Gorman To: Oracle-L (E-mail) Sent: Friday, August 05, 2005 5:42 PM Subject: Re: lock_sga error Magnus, I was asking why you thought you wanted to get your shared memory to stay resident? -Tim on 8/3/05 1:28 PM, Magnus Andersen at Magnus.Andersen@xxxxxxxxxxxxxxx wrote: Thanks Kevin. I wanted to get my shared memory to stay resident and I did implement hugtlb. I am not using the indirect_data_buffers since I only have access to a 1.7 GB SGA at this point. Magnus -----Original Message----- From: Kevin Closson [mailto:kevinc@xxxxxxxxxxxxx] Sent: Wednesday, August 03, 2005 2:54 PM To: Oracle-L (E-mail) Subject: RE: lock_sga error lock_sga is an OSD init.ora param...it only means something at the port level.. for instance lock_sga was implemented on the DYNIX/ptx port, but use_ism was implemented on Sol instead... Either way, the hope is that the OS complements this param with shared page tables and hard-locked SysV SHMEM... neither of which really related to Linux much. Are you sure you can boot of that init.ora file even with lock_sga commented out? Now, if you want your shared memory to stay resident (novel concept, I know, but it is a bit new to linux) you have to fiddle around with HUGE_TLB and so on. Also, if using indirect_data_buffers, you will need to use ramfs over shmfs because the latter is pageable ... ------------------------------------------------------------------------ From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Tim Gorman Sent: Wednesday, August 03, 2005 9:09 AM To: Oracle-L (E-mail) Subject: Re: lock_sga error Why do you want to do this? on 7/25/05 7:43 AM, Magnus Andersen at Magnus.Andersen@xxxxxxxxxxxxxxx wrote: Hi All, I'm trying to lock my sga in memory on a RedHat Linux 3 AS server. When I try to start the database with the "lock_sga=true" paramerter in my init file I get the following error: SQL> startup nomount; ORA-27102: out of memory Linux Error: 12: Cannot allocate memory SQL> Any ideas? Thanks, Magnus Andersen Systems Administrator / Oracle DBA Walker & Associates, Inc.
- Re: lock_sga error
- From: Tim Gorman
- Re: lock_sga error