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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] Memory management livelock
Date: Fri, 3 Oct 2008 14:29:09 +1000
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Cc: Mikulas Patocka <mpatocka@redhat.com>, linux-kernel@vger.kernel.org,
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       chris@arachsys.com
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On Friday 03 October 2008 14:17, Andrew Morton wrote:
> On Fri, 3 Oct 2008 14:07:55 +1000 Nick Piggin <nickpiggin@yahoo.com.au> 
> > Possibly a new mutex in the address_space?
>
> That's another, umm 24 bytes minimum in the address_space (and inode).
> That's fairly ouch, which is why Miklaus did that hokey bit-based
> thing.

Well yeah, it would be a bit based mutex in mapping->flags with
hashed waitqueues. Like Miklaus's.


> > Yeah... I went to break the sync/async cases into two, but it looks like
> > it may not have been worthwhile. Just another branch might be the best
> > way to go.
>
> Yup.  Could add another do-this flag in the writeback_control, perhaps.
> Or even a function pointer.

Yeah... possibly we could just _always_ do the PAGECACHE_TAG_FSYNC thing
if mode != WB_SYNC_NONE. I think if we had the infrastructure there to
do it all, it should always be something we want to do for data integrity
writeout.
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