RE: why swap at all?

[Piszcz, Justin Michael]

If one has 16GB of ram, would he or she want to use swap?
Would it slow the system down?


-----Original Message-----
From: linux-kernel-owner@xxxxxxxxxxxxxxx
[mailto:linux-kernel-owner@xxxxxxxxxxxxxxx] On Behalf Of Matthias
Schniedermeyer
Sent: Wednesday, May 26, 2004 8:27 AM
To: Nick Piggin
Cc: linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: why swap at all?

On Wed, May 26, 2004 at 09:19:40PM +1000, Nick Piggin wrote:
> Matthias Schniedermeyer wrote:
> >On Wed, May 26, 2004 at 08:33:28PM +1000, Nick Piggin wrote:
> >
> >>Matthias Schniedermeyer wrote:
> >>
> 
> >>>In my personal machine i have 3GB of RAM and i regularly create
> >>>DVD-ISO-Images (about 2 per day). After creating an image (reading
up to
> >>>4,4GB and writing up to 4,4GB) the cache is 100% trashed(1). With
swap
> >>>it would be even more trashed then it is without swap(1).
> >>>
> >>
> >>I don't disagree that you could find a situation where swap
> >>is worse than no swap. I don't understand what you mean by
> >>trashed and more trashed though :)
> >
> >
> >trashed means "everything i need(tm)" is paged out
(mozilla/konsole/xine
> >...)
> >
> >with swap the data-part of running programs was swapped out, without
> >swap only the program-part is thrown out of memory as the data-part
> >can't be moved anywhere else.
> >
> >I have a 10KPRM SCSI-HDD, i can here what my system is doing. :-)
> >
> 
> OK, this is obviously bad. Do you get this behaviour with 2.6.5
> or 2.6.6? If so, can you strace the program while it is writing
> an ISO? (just send 20 lines or so). Or tell me what program you
> use to create them and how to create one?

program: mkisofs
kernel: 2.4.4-2.4.25, 2.6.4-2.6.6
(To say it in other words, i never (seen/felt) a difference in 3 years.
So if there is a difference i just didn't realized there is one)
The current kernel is 2.6.5 as 2.6.6 sometimes just "hangs"

Just throw together some lage files (My files are all >= 350MB, the
"typical" case is about 4-5files with 800-1000MB each) and then
mkisofs -J -r -o <image> <source-dir>
I store the image files on another HDD to get best possibel throughput.
My HDDs (these are "normal" IDE-HDDs) are capable of delivering about
35-40MB/s, the last time i measured i got about 70MB/s aggregated
throughput while creating an image-file.



Bis denn

-- 
Real Programmers consider "what you see is what you get" to be just as 
bad a concept in Text Editors as it is in women. No, the Real Programmer
wants a "you asked for it, you got it" text editor -- complicated, 
cryptic, powerful, unforgiving, dangerous.

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