Subject: Re: Flag MAP_NORESERVE for mmap() implemented in NetBSD 3.0?
To: Christian Biere <>
From: SODA Noriyuki <>
List: current-users
Date: 11/15/2006 19:46:34
>>>>> On Wed, 15 Nov 2006 11:01:31 +0100,
      Christian Biere <> said:

>> Now any clues whether NetBSD does overcommit during memory allocations like
>> Linux does?

> I don't think it does. 

Well, the following behavior is called "overcommitting".
i.e. NetBSD (and all Mach derived VMs) does overcommit for now.

> At least, I can mmap() 1 GiB with MAP_ANON|MAP_PRIVATE
> without having that much RAM and swap being disabled. The program crashes
> during memset() then. With swap enabled it doesn't crash.  So there's no
> guarantee that the mapped memory is actually accesible or available.

See also kern/12451