Re: Swap or I/O Improvement in Fedora 8? - Linux

This is a discussion on Re: Swap or I/O Improvement in Fedora 8? - Linux ; Hi, (Sorry if this reply post becomes a new topic, I found it missing when I refresh my news reader.) General Schvantzkopf wrote: > They both use the same kernel so there shouldn't be any difference in the > swap ...

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Thread: Re: Swap or I/O Improvement in Fedora 8?

  1. Re: Swap or I/O Improvement in Fedora 8?

    Hi,

    (Sorry if this reply post becomes a new topic, I found it missing when I
    refresh my news reader.)

    General Schvantzkopf wrote:
    > They both use the same kernel so there shouldn't be any difference in the
    > swap algorithms. The memory usage might be different, if you are using
    > less memory with F8 then you would do less swapping. How much memory do
    > you actually need? You really really don't want to be swapping, buy more
    > RAM.


    I was testing some out-of-core applications which can use 32GB of RAM,
    depending on the problem size I provided in the command line argument (in
    most cases, the problems were N x N matrix algorithms where N can be 64K, or
    even more). So I suppose common motherboards for PCs won't be supporting
    that much RAM anyway.

    I found that Fedora 8 (64-bit version) could run up to 5 times as fast as
    Fedora 7 (64-bit version), depending on the application. For the memory
    usage, Fedora 8 used around 120MB RAM while Fedora 7 used about 210MB. So in
    my 2GB RAM PC, I got around 1.9GB under Fedora 8, and 1.8GB under Fedora 7.
    Considering I was running a program needing 16GB to 32GB RAM, does this
    100MB make such a big difference?

    Best Regards,
    LaBird (Benny).
    [Email: Remove all underscores to get the correct address.]



  2. Re: Swap or I/O Improvement in Fedora 8?

    On Tue, 26 Feb 2008 00:59:03 +0800, LaBird wrote:

    > Hi,
    >
    > (Sorry if this reply post becomes a new topic, I found it missing when I
    > refresh my news reader.)
    >
    > General Schvantzkopf wrote:
    >> They both use the same kernel so there shouldn't be any difference in
    >> the swap algorithms. The memory usage might be different, if you are
    >> using less memory with F8 then you would do less swapping. How much
    >> memory do you actually need? You really really don't want to be
    >> swapping, buy more RAM.

    >
    > I was testing some out-of-core applications which can use 32GB of RAM,
    > depending on the problem size I provided in the command line argument
    > (in most cases, the problems were N x N matrix algorithms where N can be
    > 64K, or even more). So I suppose common motherboards for PCs won't be
    > supporting that much RAM anyway.
    >
    > I found that Fedora 8 (64-bit version) could run up to 5 times as fast
    > as Fedora 7 (64-bit version), depending on the application. For the
    > memory usage, Fedora 8 used around 120MB RAM while Fedora 7 used about
    > 210MB. So in my 2GB RAM PC, I got around 1.9GB under Fedora 8, and 1.8GB
    > under Fedora 7. Considering I was running a program needing 16GB to 32GB
    > RAM, does this 100MB make such a big difference?
    >
    > Best Regards,
    > LaBird (Benny).
    > [Email: Remove all underscores to get the correct address.]


    When you do a free how much of your swap space is used with F7 and F8?


  3. Re: Swap or I/O Improvement in Fedora 8?

    Hi,

    "General Schvantzkopf" wrote in message
    news:Rr2dnfrmLsM6xF7anZ2dnUVZ_gidnZ2d@comcast.com. ..
    >
    > When you do a free how much of your swap space is used with F7 and F8?
    >


    Thanks for your help first.
    Do you mean after running the program? I need to collect it then.
    When I boot up using the same machine (Athlon64 Dual Core), both versions do
    not eat up any swap space, but the memory usage is different:

    F7(64-bit):
    Mem: (Total) 1930264 (Used) 237968 (Free) 1692296 (Shared) 0 (Buffers) 11264
    (Cached) 120424
    -/+ buffers/cache: (Used) 106280 (Free) 1823984
    Swap: (Total) 33551712 (Used) 0 (Free) 33551712

    F8(64-bit):
    Mem: (Total) 1933196 (Used) 127240 (Free) 1805956 (Shared) 0 (Buffers) 7696
    (Cached) 46952
    -/+ buffers/cache: (Used) 72592 (Free) 1860604
    Swap: (Total) 33551712 (Used) 0 (Free) 33551712

    Both are booted using runlevel 3, but seems the values do change every time,
    except for the swap usage.

    Best Regards,
    LaBird (Benny).
    [Email: Remove all underscores to get the correct address.]



  4. Re: Swap or I/O Improvement in Fedora 8?

    On Wed, 27 Feb 2008 01:33:45 +0800, LaBird wrote:

    > Hi,
    >
    > "General Schvantzkopf" wrote in message
    > news:Rr2dnfrmLsM6xF7anZ2dnUVZ_gidnZ2d@comcast.com. ..
    >>
    >> When you do a free how much of your swap space is used with F7 and F8?
    >>
    >>

    > Thanks for your help first.
    > Do you mean after running the program? I need to collect it then. When I
    > boot up using the same machine (Athlon64 Dual Core), both versions do
    > not eat up any swap space, but the memory usage is different:
    >
    > F7(64-bit):
    > Mem: (Total) 1930264 (Used) 237968 (Free) 1692296 (Shared) 0 (Buffers)
    > 11264 (Cached) 120424
    > -/+ buffers/cache: (Used) 106280 (Free) 1823984 Swap: (Total) 33551712
    > (Used) 0 (Free) 33551712
    >
    > F8(64-bit):
    > Mem: (Total) 1933196 (Used) 127240 (Free) 1805956 (Shared) 0 (Buffers)
    > 7696 (Cached) 46952
    > -/+ buffers/cache: (Used) 72592 (Free) 1860604 Swap: (Total) 33551712
    > (Used) 0 (Free) 33551712
    >
    > Both are booted using runlevel 3, but seems the values do change every
    > time, except for the swap usage.
    >
    > Best Regards,
    > LaBird (Benny).
    > [Email: Remove all underscores to get the correct address.]


    Yes I mean when running the program, if you were using any swap space
    after a boot it would be game over.

    Swapping is a function of the kernel and both F7 and F8 are running a
    2.6.23 kernel. It's possible that there is some patch that they've
    applied to the F8 kernel that changes the memory management algorithm.

    An experiment that you could try is to use your own kernel. Download the
    latest kernel from kernel.org then copy the .config file from

    /usr/src/kernels/2.6.23.15-137.fc8-x86_64/.config

    do a

    make gconfig
    which will bring up the configuration GUI and let you make any changes
    that you want.

    Then do

    make -j 2
    make modules_install
    make install

    Do it on both F7 and F8. This will give you identical kernels on both
    systems. You could also try the 2.6.24 kernel vs a 2.6.23, it's possible
    that RH used a memory management patch on the 2.6.23 F8 kernel that's now
    in the mainstream .24 kernel.

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