Re: [RFC][PATCH 1/3] tracking dirty pages in shared mappings -V4

[Andy Whitcroft <apw@shadowen.org>]

Andrew Morton wrote:
> Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> 
>>
>>From: Peter Zijlstra <a.p.zijlstra@chello.nl>
>>
>>People expressed the need to track dirty pages in shared mappings.
>>
>>Linus outlined the general idea of doing that through making clean
>>writable pages write-protected and taking the write fault.
>>
>>This patch does exactly that, it makes pages in a shared writable
>>mapping write-protected. On write-fault the pages are marked dirty and
>>made writable. When the pages get synced with their backing store, the
>>write-protection is re-instated.
>>
>>It survives a simple test and shows the dirty pages in /proc/vmstat.
> 
> 
> It'd be nice to have more that a "simple test" done.  Bugs in this area
> will be subtle and will manifest in unpleasant ways.  That goes for both
> correctness and performance bugs.

I'll kick off some testing of this stack and see what occurs.  Should
appear on t.k.o in due time.

Cheers.

-apw

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