From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:34314)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <rth7680@gmail.com>) id 1avow9-00013y-2j
	for qemu-devel@nongnu.org; Thu, 28 Apr 2016 12:37:09 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <rth7680@gmail.com>) id 1avow3-0001xe-VL
	for qemu-devel@nongnu.org; Thu, 28 Apr 2016 12:37:09 -0400
Received: from mail-qg0-x243.google.com ([2607:f8b0:400d:c04::243]:35374)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <rth7680@gmail.com>) id 1avow3-0001xV-Rx
	for qemu-devel@nongnu.org; Thu, 28 Apr 2016 12:37:03 -0400
Received: by mail-qg0-x243.google.com with SMTP id b14so5921205qge.2
	for <qemu-devel@nongnu.org>; Thu, 28 Apr 2016 09:37:03 -0700 (PDT)
Sender: Richard Henderson <rth7680@gmail.com>
References: <1461107270-19234-1-git-send-email-cota@braap.org>
	<1461107270-19234-12-git-send-email-cota@braap.org>
	<571A6245.4070209@twiddle.net> <571A82B8.5080908@twiddle.net>
	<20160422235738.GA2410@flamenco> <571D2280.3040908@twiddle.net>
	<20160424220651.GB1122@flamenco> <20160427024318.GA22518@flamenco>
From: Richard Henderson <rth@twiddle.net>
Message-ID: <2e5fd7bf-7f56-a188-e9a7-84fbdd05bc45@twiddle.net>
Date: Thu, 28 Apr 2016 09:37:00 -0700
MIME-Version: 1.0
In-Reply-To: <20160427024318.GA22518@flamenco>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Subject: Re: [Qemu-devel] [PATCH v3 11/11] translate-all: add tb hash bucket
 info to 'info jit' dump
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel/>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: "Emilio G. Cota" <cota@braap.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>, MTTCG Devel <mttcg@greensocs.com>, =?UTF-8?Q?Alex_Benn=c3=a9e?= <alex.bennee@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, Peter Crosthwaite <crosthwaite.peter@gmail.com>, Peter Maydell <peter.maydell@linaro.org>, Sergey Fedorov <serge.fdrv@gmail.com>

On 04/26/2016 07:43 PM, Emilio G. Cota wrote:
> How does the following look?
> 
> Example with good hashing, i.e. func5(phys_pc, pc, flags):
> TB count            704242/1342156
> [...]
> TB hash buckets     386484/524288 (73.72% used)
> TB hash occupancy   32.57% avg chain occupancy. Histogram: 0-10%▆▁█▁▁▅▁▃▁▁90-100%
> TB hash avg chain   1.02 buckets. Histogram: 1█▁▁3
> 
> Example with bad hashing, i.e. func5(phys_pc, 0, 0):
> TB count            710748/1342156
> [...]
> TB hash buckets     113569/524288 (21.66% used)
> TB hash occupancy   10.24% avg chain occupancy. Histogram: 0-10%█▁▁▁▁▁▁▁▁▁90-100%
> TB hash avg chain   2.11 buckets. Histogram: 1▇▁▁▁▁▁▁▁▁▁93
> 
> Note that:
> 
> - "TB hash avg chain" does _not_ count empty buckets. This gives
>   an idea of how many buckets a typical hit goes through.
> 
> - "TB hash occupancy" _does_ count empty buckets. It is called
>   "avg chain occupancy" and not "avg occupancy" because the
>   counts are only valid per-chain due to the seqlock protecting
>   each chain.

Looks really good.


r~