On our Tru64 boxes, we usually turn off vm_swap_eager to make is do lazy swap. It depend on what you wanted to achieve. As Tru64 is running on the Alpha which is a truly 64 bit OS and CPU, having more swap is better than less as your processes can really use up whatever memory you can put into your box. I have blast and ssaha jobs using ~20GB of memory. LAI Loong-Fong On Mar 31, 2004, at 1:27 AM, Tim Cutts wrote: > > On 30 Mar 2004, at 19:00, Dan Bolser wrote: > >> On Wed, 31 Mar 2004, LAI Loong Fong wrote: >> >>> Hmm strange that you are getting 2GB per process, my large job >>> normally >>> died around the 3GB on a standard linux kernel. Size of swap got >>> nothing to do with this limit especially when you already has 4GB of >> >> This was just a rumour I heard about true64. Kernel limits physical >> memory >> to the size of the swap for some reason. > > I think you are referring to Tru64's two methods of swap allocation. > There is a kernel tunable parameter in Tru64 called vm_swap_eager. > This can be set to one of two modes. > > As I understand it, it works like this: > > Most programs allocate far more memory than they use. This can cause > problems, so most operating systems overcommit memory and swap. The > problem with this approach is that if you malloc a lot of memory, the > malloc may succeed, but when you later try to use it, the OS cannot > fulfil its promises, and really nasty things happen. > > Tru64 can operate in this way, just like other operating systems (and > is the way we have it set). But it might be set to its alternative > mode, whereby malloc actually immediately allocates from swap. If > there isn't sufficient swap available, the malloc fails immediately. > In this mode, memory allocated is *guaranteed* to be available to the > application, which for certain applications can make things more > reliable. The machine will never run out of memory at a time other > than at the point of memory allocation. > > I seem to remember that IRIX has a similar tunable parameter for > memory use. > > Tim > > -- > Dr Tim Cutts > Informatics Systems Group > Wellcome Trust Sanger Institute > Hinxton, Cambridge, CB10 1SA, UK > > _______________________________________________ > Bioclusters maillist - Bioclusters@bioinformatics.org > https://bioinformatics.org/mailman/listinfo/bioclusters