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Re: Swap priority in Debian

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On Saturday 25 August 2018 04:29 PM, Reco wrote:
> 	Hi.
>
> On Sat, Aug 25, 2018 at 09:42:31AM +0530, Subhadip Ghosh wrote:
>> Hi,
>>
>> I am a Debian testing user. Recently I am experiencing freezing on my Debian
>> system intermittently and during troubleshooting the same, I found out that
>> the I have a swap partition with priority set to -2.
> Same here with stable.
>
>
>> But according to the below manpage:
>>
>> https://manpages.debian.org/stretch/mount/swapon.8.en.html
>>
>> swap priority should be between -1 and 32767.
> So swapon(8) utility has this restriction. Note that the system call
> itself - swapon(2) merely interprets swap priority as a signed integer,
> so any priority number is actually possible (within integer limits of
> course).
>
>
>> I have a swappiness value of 60 but I don't remember seeing the swap
>> being used at all recently, the used swap is always 0%.
> A hint. They invented this wonderful thing called sysstat decades ago so
> you don't have to remember your swap usage, along with other things
> sysstat gathers.
>
>
>> My question is, do you think that the -2 priority is stopping the swap
>> partition from actually being used and because of that, the system is
>> getting frozen when the memory usage is high?
> No, it definitely does not work this way.
> A swap priority only comes into play once you have multiple instances of
> swaps. If you have a single swap partition/lv/file, a priority value is
> meaningless.
>
> A system freezes, on the other hand (did I mention sysstat?), could
> indicate heavy swapping, barrier writes, kernel bugs (12309, anyone?),
> oom killer invocations, overheating and many other things.
> A good starting point would be kernel message log (aka
> /var/log/kern.log) from the time of this freeze.
Thanks for the suggestion. I checked the kern.log but did not find any 
suspicious log, in fact no entry from that exact time frame when the 
last freeze happened. Do you have any other suggestions to troubleshoot 
the freezes?

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Thread

Swap priority in Debian Subhadip Ghosh <subhadip.sky@gmail.com> - 2018-08-25 06:20 +0200
  Re: Swap priority in Debian Dekks Herton <dekkzz78@gmail.com> - 2018-08-25 09:50 +0200
    Re: Swap priority in Debian Subhadip Ghosh <subhadip.sky@gmail.com> - 2018-08-25 10:20 +0200
      Re: Swap priority in Debian Rick Thomas <rbthomas@pobox.com> - 2018-08-25 11:50 +0200
        Re: Re: Swap priority in Debian dekkzz78@gmail.com - 2018-08-25 13:10 +0200
  Re: Swap priority in Debian Reco <recoverym4n@gmail.com> - 2018-08-25 13:10 +0200
    Re: Swap priority in Debian Subhadip Ghosh <subhadip.sky@gmail.com> - 2018-08-25 14:40 +0200
      Re: Swap priority in Debian Reco <recoverym4n@gmail.com> - 2018-08-25 18:20 +0200

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