Subject: Re: Swap overcommit (was Re: Replacement for grep(1) (part 2))
To: Daniel C. Sobral <dcs@newsguy.com>
From: Matthew Dillon <dillon@apollo.backplane.com>
List: tech-kern
Date: 07/15/1999 21:57:31
:Technical follow-up:
:
:Contrary to what I previously said, a number of tests reveal that
:Solaris, indeed, does not overcommit. All non-read only segments,
:and all malloc()ed memory is reserved upon exec() or fork(), and the
:reserved memory is not allowed to exceed the total memory. It makes
:extensive use of read only DATA segments, and has a NON_RESERVE
:mmap() flag.
:
:Though the foot firmly planted in my mouth ought to prevent me from
:saying anything else, I must say that it does explain a few things
:to me...
:
:--
:Daniel C. Sobral (8-DCS)
:dcs@newsguy.com
Something is weird here. If the solaris people are using a
SWAPSIZE + REALMEM VM model, they have to allow the
allocated + reserved space go +REALMEM bytes over available swap
space. If not they are using only a SWAPSIZE VM model.
Wait - does Solaris normally use swap files or swap partitions?
Or is it that weird /tmp filesystem stuff? If it normally uses swap
files and allows holes then that explains everything.
-Matt
Matthew Dillon
<dillon@backplane.com>