Date: Wed, 7 Oct 2009 12:25:03 -0700 (PDT)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Nick Piggin <npiggin@suse.de>
cc: Jens Axboe <jens.axboe@oracle.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       linux-fsdevel@vger.kernel.org,
       Ravikiran G Thirumalai <kiran@scalex86.org>,
       Peter Zijlstra <peterz@infradead.org>
Subject: Re: [rfc][patch] store-free path walking
In-Reply-To: <20091007164622.GX30316@wotan.suse.de>
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On Wed, 7 Oct 2009, Nick Piggin wrote:
> 
> Oh I did that, used a "seqcount" which is the bare sequence counter
> (and update it while holding d_lock).

Oh, I didn't notice, for a really silly reason: I looked at how you had 
changed DNAME_INLINE_LEN_MIN on 64-bit, and noticed that you were using 8 
bytes for your sequence lock.

But that's only true due to the padding things, and the seqcount itself is 
indeed just 4 bytes. 

Sad. But we do have the added requirement that we want to keep the 
commonly used fields together in the same cacheline, so maybe it's 
unavoidable.

		Linus
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