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From: Richard Henderson <rth@twiddle.net>
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Date: Wed, 6 Apr 2016 11:27:54 -0700
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Subject: Re: [Qemu-devel] [PATCH 07/10] tb hash: hash phys_pc, pc,
	and flags with xxhash
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To: Paolo Bonzini <pbonzini@redhat.com>, "Emilio G. Cota" <cota@braap.org>
Cc: MTTCG Devel <mttcg@greensocs.com>, Peter Maydell <peter.maydell@linaro.org>, Peter Crosthwaite <crosthwaite.peter@gmail.com>, QEMU Developers <qemu-devel@nongnu.org>, Sergey Fedorov <serge.fdrv@gmail.com>, =?UTF-8?Q?Alex_Benn=c3=a9e?= <alex.bennee@linaro.org>

On 04/06/2016 11:23 AM, Paolo Bonzini wrote:
> Perhaps better is to always use a three-word xxhash, but pick the 64-bit
> version if any of phys_pc and pc are 64-bits.  The unrolling would be
> very effective, and the performance penalty not too important (64-bit on
> 32-bit is very slow anyway).

True.

It would also be interesting to put an average bucket chain length into the
"info jit" dump, so that it's easy to see how the hashing is performing for a
given guest.


r~