[894] in SIPB_Linux_Development
Re: What the ^$#@ just happened?
daemon@ATHENA.MIT.EDU (Greg Hudson)
Tue Jan 10 11:40:49 1995
To: jered@MIT.EDU
Cc: linux-dev@MIT.EDU
In-Reply-To: Your message of "Tue, 10 Jan 1995 10:46:44 EST."
<199501101546.KAA00396@vorlon.mit.edu>
Date: Tue, 10 Jan 1995 11:41:01 -0500
From: Greg Hudson <ghudson@MIT.EDU>
> I woke up at 10:20 this morning to the not so pleasant sound of my
> machine thrashing. I suppose this is a common experience for Linux
> users with little memory, but I have 32 MB, and more importantly, NO
> SWAP FILE. So I don't think it was swapping. The system was
> unusably slow for about 2 more minutes, and then not working too
> well, so I rebooted.
Linux has demand-paged executables, so that pages of executables are
not always read in at any given time. If some process is chewing up
all of your memory, Linux will push executable pages out of its buffer
cache and swap (in the demand-paging sense) badly. (There are some
heuristics in the kernel to avoid invalidating buffer cache pages too
quickly, but if a process is really chewing up all of your virtual
memory, then it shrinks the buffer cache to approximately 0 at some
point. Might be better to set a hard minimum, or something, but I
don't think that's done.)
I don't know what happened in this particular instance, though.
