RE: Paging file

["Goodbar, Loyd (AFS-Water Valley)" <LGoodbar@xxxxxxxxxxxxxx>]

If I dynamically allocate 16MB of memory using %alloc in a batch job, where
is that 16MB stored if the job is paged to disk? Does SLS allocate a pointer
for the program's "one-time" use?

Thanks,
Loyd

-----Original Message-----
From: James Rich [mailto:james@eaerich.com]
Sent: Thursday, October 31, 2002 11:35 AM
To: midrange-l@midrange.com
Subject: Re: Paging file


On Thu, 31 Oct 2002 vhamberg@attbi.com wrote:

> Say you have a 6meg file. On a *nix swap partition it'll
> be a continuous block of 6meg, right? On a 400, it'll probably be in 6
> 1meg extents, on 6 separate drives. All 6 will go to their extent at
> basically the same time, so seek time is about the same, since it's in
> parallel. the actual elapsed time to physically read the data off
> disk, assuming the same rotational speed, is about 1/6th
> that of the long, 6meg file on a single platter.

In this case I agree.  But is swap data that large?  I don't really know. As
the amount you read decreases the seek time becomes a bigger and bigger
factor.  Even 6MB is small enough that (if it is one file, not 3 2MB
files) a single disk may outperform several because you only have to seek
once instead of several times.  This is interesting enough that I'm going to
go bother the filesystem guys at SGI and see what they think...

James Rich