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Date: Fri, 24 Aug 2012 16:57:08 +0200
From: Luigi Rizzo <rizzo@iet.unipi.it>
To: Alan Cox <alc@rice.edu>
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Cc: alc@freebsd.org, current@freebsd.org
Subject: Re: less aggressive contigmalloc ?
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On Fri, Aug 24, 2012 at 12:43:33AM -0500, Alan Cox wrote:
> On 08/23/2012 12:45, Luigi Rizzo wrote:
> >On Thu, Aug 23, 2012 at 12:08:40PM -0500, Alan Cox wrote:
> >...
> >>>yes i do see that.
> >>>
> >>>Maybe less aggressive with M_NOWAIT but still kills processes.
> >>Are you compiling world with MALLOC_PRODUCTION?  The latest version of
> >whatever the default is. But:
> >
> >>jemalloc uses significantly more memory when debugging options are
> >>enabled.  This first came up in a thread titled "10-CURRENT and swap
> >>usage" back in June.
> >>
> >>Even at its most aggressive, M_WAITOK, contigmalloc() does not directly
> >>kill processes.  If process death coincides with the use of
> >>contigmalloc(), then it is simply the result of earlier, successful
> >>contigmalloc() calls, or for that matter any other physical memory
> >>allocation calls, having depleted the pool of free pages to the point
> >>that the page daemon runs and invokes vm_pageout_oom().
> >does it mean that those previous allocations relied on memory overbooking ?
> 
> Yes.
> 
> >Is there a way to avoid that, then ?
> 
> I believe that malloc()'s default minimum allocation size is 4MB.  You 
> could reduce that.
> 
> Alternatively, you can enable MALLOC_PRODUCTION.

i tried this, and as others mentioned it makes life
better and reduces the problem but contigmalloc still triggers
random process kills.

Thanks for the hints.

cheers
luigi