On Wed, Apr 3, 2013 at 9:50 PM, Simon Jeons <simon.jeons@xxxxxxxxx> wrote: >> FAQ >> ... >> * How do you calculate a minimum useful reserve? >> >> A user or the admin needs enough memory to login and perform >> recovery operations, which includes, at a minimum: >> >> sshd or login + bash (or some other shell) + top (or ps, kill, etc.) >> >> For overcommit 'guess', we can sum resident set sizes (RSS). >> On x86_64 this is about 8MB. >> >> For overcommit 'never', we can take the max of their virtual sizes >> (VSZ) >> and add the sum of their RSS. >> On x86_64 this is about 128MB. > > > 1.Why has this different between guess and never? The default, overcommit 'guess' mode, only needs a reserve for what the recovery programs will typically use. Overcommit 'never' mode will only successfully launch an app when it can fulfill all of its requested memory allocations--even if the app only uses a fraction of what it asks for. > 2.You just test x86/x86_64, other platforms also will use memory overcommit, > did you test them? No, I haven't. Unfortunately, I don't currently have any other platforms to test with. I'll see what I can do. Thanks, Andrew -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>