Subject: Re: Replacement for grep(1) (part 2)
To: Robert Elz <kre@munnari.OZ.AU>
From: Daniel C. Sobral <email@example.com>
Date: 07/15/1999 00:53:17
Robert Elz wrote:
> Date: Tue, 13 Jul 1999 14:14:52 -0700 (PDT)
> From: Matthew Dillon <firstname.lastname@example.org>
> Message-ID: <199907132114.OAA80781@apollo.backplane.com>
> | If you don't have the disk necessary for a standard overcommit model to
> | work, you definitely do not have the disk necessary for a non-overcommit
> | model to work.
> This is based upon your somewhat strange definition of "work". I assure
> you that I have run many systems which don't use overcommit, and which I
> quite frequently run into "out of VM" conditions, and which I can assure
> you, work just fine. When they're getting to run out of VM, the system
> is approaching paging death, which is as you'd expect (they're overloaded).
> That is, adding more VM (more swap space) would be counterproductive.
Would you care to name such systems? And, btw, a system consuming
all memory is *not* necessarily approaching paging death. More
likely, it is just storing a lot of data in the swap which will
never be used (which is the whole point of overcommit in first
place), and, thus, never paged in.
> I have no doubt but that you can dream up scenarios where you pander to
> the laziness of programmers, and make using huge VM space with little
> of it actually allocated anywhere (or ever touched) then you would indeed
> need monstrous amounts of paging space, most of which is never actually
> used for anything - personally I prefer to have the programmers think
> a little more about the memory footprint of their data structures. Not
> only does this reduce the VM footprint, it will also usually vastly
> improving the paging characteristics. Most applications which simply
> scatter data through a huge VM space simply stop being useable as soon
> as their RSS exceeds available physical memory - that is, if they start
> paging, they die (become comatose might be a better description).
> A little intelligent though as to how to actually make use of the mem
> resources can make a huge difference.
Fine. Stay with the allocation of swap for DATA/BSS of each instance
of the same program you are running. That alone is enough.
Daniel C. Sobral (8-DCS)
"Would you like to go out with me?"
"I'd love to."
"Oh, well, n... err... would you?... ahh... huh... what do I do