Re: [rfc][patch] store-free path walking

Linus Torvalds
2009-10-07T19:26:37Z

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