Re: Memory pages not released by the filesystem after a truncate

Houssem Daoud <houssem.daoud@xxxxxxxxxx> · Tue, 12 Jul 2016 17:12:31 -0400



    The situation is the following: Filesystem anonymous pages are
      consuming all the available memory and only 100 MB is left to the
      system. 

    
    The network driver, which allocates memory objects for Jumbo
      frames, needs more than 100 MB to run correctly.  If a burst of
      networks packets arrive together, the available memory is fully
      consumed and the new packets start to be dropped.
    This situation wouldn't happen if the "useless" pages of the
      filesystem were released just after the truncate operation.
    What is the point of keeping truncated pages in memory ? Is that
      a choice made by the kernel developers or there is something wrong
      in the filesystem implementation ?

    
    On 16-07-06 12:29 PM, Mulyadi Santosa
      wrote:

    
      Hi
        

        Trying to help here:
        You said you wanna do atomic
          allocation. But then you said you want to allocate around ~100
          MB contiguous memory region.
        

        IIRC, if you want to do atomic
          allocation, usually it can not be that big. I am not sure how
          large, but surely not reaching 100 MB. For that size, I think
          you should rely on vmalloc.
        

        But, for clarification, maybe you
          should also post your full content of  /proc/buddyinfo and
          /proc/meminfo 
        

          -- 

        
        regards,

          
          Mulyadi Santosa

          Freelance Linux trainer and consultant

          
          blog: the-hydra.blogspot.com

          training: mulyaditraining.blogspot.com
        
        
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