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Date: Thu, 2 Apr 2009 11:43:05 +0200 From: Nick Piggin <npiggin@...e.de> To: Al Viro <viro@...IV.linux.org.uk> Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [rfc] scale dcache locking On Wed, Apr 01, 2009 at 03:23:12PM +0100, Al Viro wrote: > On Mon, Mar 30, 2009 at 02:55:39AM +1100, npiggin@...e.de wrote: > > This is my sketch for improving dcache locking scalability. So far I've > > only really been looking at core code to get an idea of how it might look, > > so most configurable functionality is broken (and unfortunately it might > > well be something in there which will cause a fundamental problem for me). > > Umm... Some of that makes obvious sense per se, some... In particular, > all of a sudden we get contention between multiple dput() on the same > dentry, which is dirt-common for directory ones. Yes that's true but I'm hoping lock hold times on d_lock aren't too long, in which case the major cost should remain just the cacheline contention. Hmm, I wanted to avoid the atomic because it tends to be covered by d_lock a lot of the time anyway so avoiding the extra locked op, and also makes concurrency a bit easier to think about. In worst case, I guess we need to reintroduce atomic refcount or have another lock for it... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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