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Date: Tue, 25 Oct 2016 16:45:15 -0400
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Subject: Re: [Qemu-devel] [RFC PATCH] qht: Align sequence lock to cache line
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To: Pranith Kumar <bobby.prani@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, "open list:All patches CC here" <qemu-devel@nongnu.org>, Alex =?iso-8859-1?Q?Benn=E9e?= <alex.bennee@linaro.org>, Markus Armbruster <armbru@redhat.com>, Richard Henderson <rth@twiddle.net>

On Tue, Oct 25, 2016 at 16:35:48 -0400, Pranith Kumar wrote:
> On Tue, Oct 25, 2016 at 4:02 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> >
> >
> >> I've written a patch (see below) to take the per-bucket sequence locks.
> >
> > What's the performance like?
> >
> 
> Applying only this patch, the perf numbers are similar to the 128
> cache line alignment you suggested.

That makes sense. Having a single seqlock per bucket is simple and fast;
note that bucket chains should be very short (we use good hashing and
automatic resize for this purpose).

		E.