RE: why swap at all?

From: Piszcz, Justin Michael (justin.piszcz_at_mitretek.org)
Date: 05/26/04

  • Next message: Denis Vlasenko: "RE: why swap at all?"
    Date:	Wed, 26 May 2004 08:34:52 -0400
    To: <linux-kernel@vger.kernel.org>
    
    

    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@vger.kernel.org
    [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Matthias
    Schniedermeyer
    Sent: Wednesday, May 26, 2004 8:27 AM
    To: Nick Piggin
    Cc: linux-kernel@vger.kernel.org
    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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  • Next message: Denis Vlasenko: "RE: why swap at all?"

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