Thanks, David. That finally anwers my (and maybe Roman's) question: How can ISM be used for PGA? Just because there's a shared (or rather, sharable) memory segment created doesn't mean it must be shared. Solaris ISM or Linux HugePages is just a name for this technology. It has all these features: (a) sharing page tables between processes, (b) large memory page size, (c) locking pages in memory (related to (a)). The name ISM emphasizes (a), while HugePages emphasizes (b). The Oracle parameter _use_ism_for_pga confused me simply because they used the term ism in it. If it was called _use_largepage_for_pga without any change in its implementation, I wouldn't ask the question. Yong Huang > From: David Miller <David.J.Miller@xxxxxxx> > > Hi Roman, > > ISM is indeed shared memory, but it is possible to allocate it and only > use it in one place, i.e. a single process's PGA. Once it's mapped into > the address space, it's just memory (at least mostly). Clearly when > this was implemented, the PGA for each process would use a different > shared memory segment so there wouldn't be collisions. > > As I mentioned before, I'm sure it was done to use large pages. Since there > are other mechanisms now, it's no longer necessary, which is why it was > obsoleted in 10.2. > > Regards, > > Dave > > Roman Podshivalov wrote, On 10/07/08 18:30: > > David, > > > > In my mind ISM is related to shared memory, could it be used for private > > memory allocation ? > > > > thanks > > --romas -- //www.freelists.org/webpage/oracle-l