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Thread: KDE nearly unresponsive when RAM full and swap is in use

  1. #21
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    Default Re: KDE nearly unresponsive when RAM full and swap is in use

    Haven't seen it during my quick read, but are you running 64bit openSUSE ?
    ° Appreciate my reply? Click the star and let me know why.

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  2. #22

    Default Re: KDE nearly unresponsive when RAM full and swap is in use

    Quote Originally Posted by Knurpht View Post
    Haven't seen it during my quick read, but are you running 64bit openSUSE ?
    Yes, I've only tried 64-bit versions of SuSE, Ubuntu, and Windows 7 in my investigation.

  3. #23
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    Default Re: KDE nearly unresponsive when RAM full and swap is in use

    On 2012-01-27 16:06, lazlojamf wrote:

    > This problem is fairly rare, and part of it is likely due to the
    > painfully mediocre (yet expensive) internet connection I have at home.
    > Perhaps the driver isn't optimal, but I'm just going to let this one go.
    > It could be worse - when I installed ubuntu, I couldn't get the ethernet
    > port to run above about 10 Mbps for some reason.


    Typical reason would be bad cable. Pair 3-6 not twisted. Would show as many
    transmission errors at high speed.

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    Carlos E. R.
    (from 11.4 x86_64 "Celadon" at Telcontar)

  4. #24
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    Default Re: KDE nearly unresponsive when RAM full and swap is in use

    On 2012-01-27 16:16, lazlojamf wrote:
    > Is there a significant benefit to using SATA 6Gbps?


    Only if the device has such a sustained write speed at that rate. I dunno,
    I have not used SSD devices.

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    Carlos E. R.
    (from 11.4 x86_64 "Celadon" at Telcontar)

  5. #25
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    Default Re: KDE nearly unresponsive when RAM full and swap is in use

    Adding more RAM would be the most sensible thing to do. If you are running out of RAM, then adding an SSD is just treating the symptom. You system will perform best if the kernel doesn't have to spend time shuffling pages around to try and make everything fit into too small a bucket. Its best just to get a bigger bucket. Adding an SSD would just allow it to shuffle faster. Adding RAM will stop the shuffling.

    Linux behaves just as you describe. If you run out of RAM and have to shuffle too much into swap it basically freezes as processes fight for resources. If you're running the out-of-memory killer, the killer will eventually start killing the hogs. Some have suggested ways to mark out some processes as more important, but no one has come up will a well performing solution that still keeps the kernel general purpose.

    It may be that your Linux ported applications use more RAM under Linux. If you've stepped up to 64bit, that may cause some bloat.

    SSD's are generally good for speeding up boot and application/file loading on the first time you access anything on the SSD. If you have plenty of RAM, on the subsequent times you access the app/fill it will already be in RAM, so the SSD will not even be accessed. So an SSD is a poor investment if you don't care about things taking a little more time to boot or first load.

    Quote Originally Posted by lazlojamf View Post
    I was originally going to upgrade my RAM, but getting an SSD might be more sensible, since I can get a 60GB drive for $90 on amazon and it will likely fix most of the problems with RAM/swap that I have.

    Given that I only have a budget for 1 SSD, I would like to know whether it would be more useful to put it in my laptop (the W510 has SATA 1.5 Gbps in the bay and 3Gbps in the primary slot) or my desktop (which has SATA 6Gbps). For the record I use both the laptop and desktop evenly, and it's no trouble to process the large datasets on the desktop when I get a chance. Is there a significant benefit to using SATA 6Gbps?

  6. #26
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    Default Re: KDE nearly unresponsive when RAM full and swap is in use

    On 01/28/2012 06:26 AM, mchnz wrote:
    > Adding more RAM would be the most sensible thing to do. If you are
    > running out of RAM, then adding an SSD is just treating the symptom.
    > You system will perform best if the kernel doesn't have to spend time
    > shuffling pages around to try and make everything fit into too small a
    > bucket. Its best just to get a bigger bucket. Adding an SSD would just
    > allow it to shuffle faster. Adding RAM will stop the shuffling.
    >
    > Linux behaves just as you describe. If you run out of RAM and have to
    > shuffle too much into swap it basically freezes as processes fight for
    > resources. If you're running the out-of-memory killer, the killer will
    > eventually start killing the hogs. Some have suggested ways to mark out
    > some processes as more important, but no one has come up will a well
    > performing solution that still keeps the kernel general purpose.
    >
    > It may be that your Linux ported applications use more RAM under Linux.
    > If you've stepped up to 64bit, that may cause some bloat.
    >
    > SSD's are generally good for speeding up boot and application/file
    > loading on the first time you access anything on the SSD. If you have
    > plenty of RAM, on the subsequent times you access the app/fill it will
    > already be in RAM, so the SSD will not even be accessed. So an SSD is a
    > poor investment if you don't care about things taking a little more time
    > to boot or first load.


    +1, absolutely!

    --
    DD
    Read about openSUSE

  7. #27
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    Default Re: KDE nearly unresponsive when RAM full and swap is in use

    Am 28.01.2012 06:26, schrieb mchnz:
    >
    > Adding more RAM would be the most sensible thing to do. If you are
    > running out of RAM, then adding an SSD is just treating the symptom.
    > You system will perform best if the kernel doesn't have to spend time
    > shuffling pages around to try and make everything fit into too small a
    > bucket. Its best just to get a bigger bucket. Adding an SSD would just
    > allow it to shuffle faster. Adding RAM will stop the shuffling.
    >

    If and only if you know the amount you can add is sufficient for the
    application, so you are right that in many cases simply adding RAM is
    the best, in some cases it is not.
    Scientific applications use a whole lot of RAM not only mathematica the
    OP uses, also GNU R, GNU Octave, Maxima to mention just a few I use
    myself, you can come easily into a situation where 20 - 100 or more GB
    are used if you solve large problems by experimenting with new
    algorithms and in most cases the underlying hardware is not even capable
    of adding so much RAM or it is simply too expensive. Adding a SSD as
    swap is a solution here which tremendously speeds up the paging (paying
    the price that it wears out sooner than under normal use).

    > Linux behaves just as you describe. If you run out of RAM and have to
    > shuffle too much into swap it basically freezes as processes fight for
    > resources. If you're running the out-of-memory killer, the killer will
    > eventually start killing the hogs. Some have suggested ways to mark out
    > some processes as more important, but no one has come up will a well
    > performing solution that still keeps the kernel general purpose.
    >
    > It may be that your Linux ported applications use more RAM under Linux.
    > If you've stepped up to 64bit, that may cause some bloat.
    >

    You will often not even be able to use that applications with the amount
    of memory mentioned without going to 64bit. It does not help here if you
    have a PAE kernel, the apps will work with a smaller size of pointers
    which limits their memory use per process and/or data structure.

    > SSD's are generally good for speeding up boot and application/file
    > loading on the first time you access anything on the SSD. If you have
    > plenty of RAM, on the subsequent times you access the app/fill it will
    > already be in RAM, so the SSD will not even be accessed. So an SSD is a
    > poor investment if you don't care about things taking a little more time
    > to boot or first load.
    >

    This is too simplistic as an answer since it does not take into account
    the use case of the OP.

    --
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  8. #28
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    Default Re: KDE nearly unresponsive when RAM full and swap is in use

    On 2012-01-28 09:50, DenverD wrote:
    >> already be in RAM, so the SSD will not even be accessed. So an SSD is a
    >> poor investment if you don't care about things taking a little more time
    >> to boot or first load.

    >
    > +1, absolutely!


    Depends... for example, I can not add more ram to my motherboard, it has
    the maximum. Or perhaps for the same price you can get more SSD memory than
    real memory, and the memory requirement is huge: perhaps adding 4 GiB makes
    no effect, it needs even more.

    --
    Cheers / Saludos,

    Carlos E. R.
    (from 11.4 x86_64 "Celadon" at Telcontar)

  9. #29

    Default Re: KDE nearly unresponsive when RAM full and swap is in use

    Quote Originally Posted by mchnz View Post
    Adding more RAM would be the most sensible thing to do. If you are running out of RAM, then adding an SSD is just treating the symptom. You system will perform best if the kernel doesn't have to spend time shuffling pages around to try and make everything fit into too small a bucket. Its best just to get a bigger bucket. Adding an SSD would just allow it to shuffle faster. Adding RAM will stop the shuffling.

    Linux behaves just as you describe. If you run out of RAM and have to shuffle too much into swap it basically freezes as processes fight for resources. If you're running the out-of-memory killer, the killer will eventually start killing the hogs. Some have suggested ways to mark out some processes as more important, but no one has come up will a well performing solution that still keeps the kernel general purpose.

    It may be that your Linux ported applications use more RAM under Linux. If you've stepped up to 64bit, that may cause some bloat.

    SSD's are generally good for speeding up boot and application/file loading on the first time you access anything on the SSD. If you have plenty of RAM, on the subsequent times you access the app/fill it will already be in RAM, so the SSD will not even be accessed. So an SSD is a poor investment if you don't care about things taking a little more time to boot or first load.
    I'm sure that your reasoning is absolutely correct here, but unfortunately, the size of these datasets is too big to fit in RAM anyway. For this reason, windows-style memory management would be the best option, so maybe I'll just visualize in windows, which doesn't seem to have a problem (except for an "out of memory error after about 16GB). I have 4GB in the laptop and 8GB in my desktop and I can easily max out the ram on the desktop by loading only part of a set in linux (for viewing, rendering, or analysis). Generally speaking, my desire to load this data is for visualization purposes only. I can easily slice the data and process it in smaller segments on a cluster, or in the background. However, to visualize a molecular dynamics simulation, it is often desirable to see the whole thing at once. It's helpful to take a look at what's happening without some kind of second-order analysis. Ultimately, I'd like to be able to render videos of these simulations all at once. In this case, I think the SSD is the best option because I know that I'm going to be swapping very frequently anyway. For any purpose other than massive data visualization, the 4GB on my laptop is more than enough.

    Hopefully this will be my last question: exactly how fast would an SSD wear out if you used it for swap? If it's on the order of 3 years with regular use, then it's worth it. But if this thing kicks the bucket after 6 months, then I'll just go with more RAM.

  10. #30
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    Default Re: KDE nearly unresponsive when RAM full and swap is in use

    On 01/28/2012 05:26 PM, lazlojamf wrote:
    > Hopefully this will be my last question: exactly how fast would an SSD
    > wear out if you used it for swap? If it's on the order of 3 years with
    > regular use, then it's worth it. But if this thing kicks the bucket
    > after 6 months, then I'll just go with more RAM.


    i don't know how it would be possible to answer that....i mean how many
    millions of writes are you gonna do in a year, month day? the SSD you
    are gonna buy: how many writes do they say it will take in a life time?

    but look (back to the original question), if you have 4 GB of RAM and 8
    GB of swap file but routinely get "out of memory error after about 16GB"
    (in Windows) then give it a 25 GB swap file or or or just how big is
    this monster? give it 100 GB of swap if that is what it takes...

    actually: when running nuclear implosion wave front propagation
    simulations i need more than my laptop....and, you do too...

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