On Tue, Apr 1, 2014 at 5:48 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 1 Apr 2014 17:41:54 -0400 KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx> wrote: > >> >> > Hmmm so 0 won't really work because it could be weirdly used to disable >> >> > shm altogether... we cannot go to some negative value either since we're >> >> > dealing with unsigned, and cutting the range in half could also hurt >> >> > users that set the limit above that. So I was thinking of simply setting >> >> > SHMMAX to ULONG_MAX and be done with it. Users can then set it manually >> >> > if they want a smaller value. >> >> > >> >> > Makes sense? >> >> >> >> I don't think people use 0 for disabling. but ULONG_MAX make sense to me too. >> > >> > Distros could have set it to [U]LONG_MAX in initscripts ten years ago >> > - less phone calls, happier customers. And they could do so today. >> > >> > But they haven't. What are the risks of doing this? >> >> I have no idea really. But at least I'm sure current default is much worse. >> >> 1. Solaris changed the default to total-memory/4 since Solaris 10 for DB. >> http://www.postgresql.org/docs/9.1/static/kernel-resources.html >> >> 2. RHEL changed the default to very big size since RHEL5 (now it is >> 64GB). Even tough many box don't have 64GB memory at that time. > > Ah-hah, that's interesting info. > > Let's make the default 64GB? 64GB is infinity at that time, but it no longer near infinity today. I like very large or total memory proportional number. But I'm open. Please let me see if anyone know the disadvantage of very large value. -- 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>