Using Linux in RAM... - Networking

This is a discussion on Using Linux in RAM... - Networking ; Christian Williamson a écrit : > > Thanks. BTW, Pascal, which group do you think I should I have posted the > original in? Sorry, I don't know the comp.os.linux.* hierarchy well enough to answer this question....

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Thread: Using Linux in RAM...

  1. Re: Using Linux in RAM...

    Christian Williamson a écrit :
    >
    > Thanks. BTW, Pascal, which group do you think I should I have posted the
    > original in?


    Sorry, I don't know the comp.os.linux.* hierarchy well enough to answer
    this question.

  2. Re: Using Linux in RAM...

    "Maxwell Lol" wrote
    > "Magnate" writes:
    >
    >> Um .... I thought files in /proc were not actually stored on the
    >> disk??

    >
    > That's correct. Every piece of hardware in UNIX is accessed through a
    > filename. In particular, /proc is a special filesystem:


    Right. So isn't the OP's concern a little misplaced? If he runs Linux with a
    ramdisk root fs, those 26,000 files in proc will still be updated at
    precisely the same pace!!

    CC


  3. Re: Using Linux in RAM...

    Pascal Hambourg wrote:
    > The Natural Philosopher a écrit :
    >>>
    >>>> well making a ramdisk and using it for swap is not hard..
    >>>
    >>> And is definitely totally useless.

    >>
    >> Why? if the OS wants to see swap, give it some..it may be happier that
    >> way than simply removing swap altogether.

    >
    > Why would the system want to see swap ? Linux does not need swap to
    > operate. AFAIK, swap space may be used for two reasons.
    >
    > 1) Free some RAM for processes or disk cache. Obviously, creating swap
    > space in RAM won't free any RAM. On the contrary, it will consume some
    > RAM even though swap is not needed.
    >
    > 2) Suspend-to-disk. Obviously again, swap space in RAM cannot be used
    > for this.


    Swap space is not used for suspend-to-disk AFAIK - that is done to a
    separate file.

    There is another use of swap space - for tmpfs filesystems.

  4. Re: Using Linux in RAM...

    On 09/19/2008 11:43 AM, David Brown wrote:
    > Pascal Hambourg wrote:
    >> The Natural Philosopher a écrit :
    >>>>
    >>>>> well making a ramdisk and using it for swap is not hard..
    >>>>
    >>>> And is definitely totally useless.
    >>>
    >>> Why? if the OS wants to see swap, give it some..it may be happier
    >>> that way than simply removing swap altogether.

    >>
    >> Why would the system want to see swap ? Linux does not need swap to
    >> operate. AFAIK, swap space may be used for two reasons.
    >>
    >> 1) Free some RAM for processes or disk cache. Obviously, creating swap
    >> space in RAM won't free any RAM. On the contrary, it will consume some
    >> RAM even though swap is not needed.
    >>
    >> 2) Suspend-to-disk. Obviously again, swap space in RAM cannot be used
    >> for this.

    >
    > Swap space is not used for suspend-to-disk AFAIK - that is done to a
    > separate file.
    >
    > There is another use of swap space - for tmpfs filesystems.


    The default for TuxOnIce (Suspend2) is to save the image in swap.
    http://www.tuxonice.net/features

  5. Re: Using Linux in RAM...

    In comp.os.linux.networking David Brown wrote:
    > Pascal Hambourg wrote:
    >> The Natural Philosopher a écrit :
    >>>>
    >>>>> well making a ramdisk and using it for swap is not hard..
    >>>>
    >>>> And is definitely totally useless.
    >>>
    >>> Why? if the OS wants to see swap, give it some..it may be happier that
    >>> way than simply removing swap altogether.

    >>
    >> Why would the system want to see swap ? Linux does not need swap to
    >> operate. AFAIK, swap space may be used for two reasons.
    >>
    >> 1) Free some RAM for processes or disk cache. Obviously, creating swap
    >> space in RAM won't free any RAM. On the contrary, it will consume some
    >> RAM even though swap is not needed.
    >>
    >> 2) Suspend-to-disk. Obviously again, swap space in RAM cannot be used
    >> for this.

    >
    > Swap space is not used for suspend-to-disk AFAIK - that is done to a
    > separate file.


    Nope swap is used for S2D, both the kernel and userspace versions
    use it. A swap partition is easier, but a swap file can be used
    also.
    Now, with the userspace S2D, I suspect you could create a swap file or
    partition, initialize it with mkswap, and tell suspend to use it,
    without actually using it for swap.

    Jerry

  6. Re: Using Linux in RAM...

    David Brown a écrit :
    >
    > Swap space is not used for suspend-to-disk AFAIK - that is done to a
    > separate file.


    Other people have replied about this subject.

    > There is another use of swap space - for tmpfs filesystems.


    This is not a specific use of swap space. tmpfs uses memory as any
    ordinary process, and as such is subject to swap under memory pressure.

  7. Re: Using Linux in RAM...

    Pascal Hambourg wrote:
    > David Brown a écrit :
    >>
    >> Swap space is not used for suspend-to-disk AFAIK - that is done to a
    >> separate file.

    >
    > Other people have replied about this subject.
    >


    And I thank them for correcting me.

    >> There is another use of swap space - for tmpfs filesystems.

    >
    > This is not a specific use of swap space. tmpfs uses memory as any
    > ordinary process, and as such is subject to swap under memory pressure.


    Technically, that's true. But perhaps as an effect of the prioritising
    of pages for swapping, combined with typical usage patterns for /tmp, it
    is often much faster to use tmpfs for /tmp even though you may need a
    larger swap file, as compared to using the same space for a /tmp partition.

    Another reason I mention it is that use of swap space is one of the big
    differences between tmpfs and other ram disks, which typically are
    allocated non-swappable memory.

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