Re: [PATCH] Allocate module.ref array dynamically

[Eric Dumazet]

Eric Dumazet a écrit :
> Takashi Iwai a écrit :
> > Hi,
> >
> > we found that the kernel module sizes and memory footprints
> > grow drastically when NR_CPUS is high.  For example, with
> > NR_CPUS=4096, SUSE kernel packages weigh over 500MB (even w/o debug
> > info).
> >
> > A part of the reason is the fixed size array in struct module.
> > The patch below fixes the problem by allocating it dynamically.
> > With the patch, the size can go down to 20MB.
> >
> >
> > Any comments/suggestions appreciated.
>
> Many attempts were done on this area on the past.

Forgot to include a link to previous attempt : http://lkml.org/lkml/2008/5/15/402

> Your patch has the drawback of using kcalloc(), while previously, 
> module_ref
> space was allocated with vmalloc().
>
> After a while, a machine could have a lot of vmalloc() space available, 
> but not enough
> physically contiguous space to fullfill a kmalloc(large_area) call.
>
> So a module load could fail, while previous code could load module.
>
> I believe Mike Travis has a better patch for this problem, partly using 
> new percpu allocator.


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