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

Avi Kivity
2010-07-16T19:40:56Z

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.