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Re: Memory released after running rsync

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On 2015-11-29, gamo <gamo@telecable.es> wrote:
> El 29/11/15 a las 21:12, William Unruh escribi?:
>> On 2015-11-29, gamo <gamo@telecable.es> wrote:
>>>
>>> Hello,
>>>
>>> I have a desktop machine with 32 GB RAM, and as expected most of
>>> the memory is used as a cache. Sometimes I have few memory free,
>>> less than 1 GB, and happens that after running 'rsync' the memory
>>> reported by 'free' as free is increased notably. So the question
>>> is: what kind of magic do the rsync program?
>>
>> memory which is unused is used by Linux as program chache. Instead of
>> releasing the program memory, the program is kept in memory in case it
>> is reused. HOwever, if some other program requires the memory, it is
>> released. Thus probably rsync uses that memory, and then releases it
>> before shutting down. Thus the memory is now free. It is no longer used
>> for program cache because that use was supreceeded by rsync, and no
>> longer used by rsync either.
>>
>> The above is just a guess.
>>>
>>> Thanks. Regards.
>>>
>
> I realized a test. One script to fill in the memory and get killed by 
> the kernel or perl.
>
> First it takes a while. Then, the computer seems hanged. I pressed ^C 
> and after a moment, the program exit and I have only 5 GB of memory 
> occupied.
>
> So, I is a bit scary, but a 'releasemem' utility is factible.

factible? 

Anyway, in storing the programs, AFAIK the data is usually not stored as
well. And a script would not work that way. It is a very small program.
Try loading ooffice, xmaple, gimp, .... That should slowly fill up your
memory as those programs ( not data) are stored for potential later use.
(That is why the second time you open libreoffice is often so much
faster than the first-- unless you have SATAIII and an SDDrive. 
Look at the free memory. Then use your script to fill up the memory, and
see what happens when you close it. 
Note that the sysstem probably started swapping which would make it seem
really really slow. 

But why do you care? The programs are cached only if that space is not
needed. Why do you want empty memory sitting there doing nothing?


>

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Memory released after running rsync gamo <gamo@telecable.es> - 2015-11-29 14:51 +0100
  Re: Memory released after running rsync William Unruh <unruh@invalid.ca> - 2015-11-29 20:12 +0000
    Re: Memory released after running rsync gamo <gamo@telecable.es> - 2015-11-29 21:56 +0100
      Re: Memory released after running rsync William Unruh <unruh@invalid.ca> - 2015-11-29 21:16 +0000
        Re: Memory released after running rsync gamo <gamo@telecable.es> - 2015-11-29 23:52 +0100
      Re: Memory released after running rsync Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2015-11-30 00:33 +0100
        Re: Memory released after running rsync gamo <gamo@telecable.es> - 2015-11-30 07:16 +0100
          Re: Memory released after running rsync Teemu Likonen <tlikonen@iki.fi> - 2015-12-01 18:04 +0200
            Re: Memory released after running rsync gamo <gamo@telecable.es> - 2015-12-01 23:49 +0100
  Re: Memory released after running rsync Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2015-11-29 18:36 -0800

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