Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault

[Avi Kivity]

On 07/16/2010 10:29 PM, H. Peter Anvin wrote:
> On 07/16/2010 11:32 AM, Avi Kivity wrote:
>    
> > How long would vmalloc_sync_all take with a few thousand mm_struct take?
> >
> > We share the pmds, yes?  So it's a few thousand memory accesses.  The
> > direct impact is probably negligible, compared to actually loading the
> > module from disk.  All we need is to make sure the locking doesn't slow
> > down unrelated stuff.
> >
> >      
> It's not the memory accesses, it's the need to synchronize all the CPUs.
>    

I'm missing something.  Why do we need to sync all cpus?  the 
vmalloc_sync_all() I'm reading doesn't.

Even if we do an on_each_cpu() somewhere, it isn't the end of the world.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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