From owner-freebsd-fs@freebsd.org  Wed Aug 29 10:14:27 2018
Return-Path: <owner-freebsd-fs@freebsd.org>
Delivered-To: freebsd-fs@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 4965510842CF;
 Wed, 29 Aug 2018 10:14:27 +0000 (UTC)
 (envelope-from freebsd@omnilan.de)
Received: from mx0.gentlemail.de (mx0.gentlemail.de [IPv6:2a00:e10:2800::a130])
 (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id BF98D859C3;
 Wed, 29 Aug 2018 10:14:26 +0000 (UTC)
 (envelope-from freebsd@omnilan.de)
Received: from mh0.gentlemail.de (mh0.gentlemail.de [78.138.80.135])
 by mx0.gentlemail.de (8.14.5/8.14.5) with ESMTP id w7TAEP4d082783;
 Wed, 29 Aug 2018 12:14:25 +0200 (CEST)
 (envelope-from freebsd@omnilan.de)
Received: from titan.inop.mo1.omnilan.net (s1.omnilan.de [217.91.127.234])
 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits))
 (No client certificate requested)
 by mh0.gentlemail.de (Postfix) with ESMTPSA id 47AABABB;
 Wed, 29 Aug 2018 12:14:25 +0200 (CEST)
Subject: Re: ZFS (ARC) performance regression in r321610
To: rainer@ultra-secure.de
Cc: freebsd-fs@freebsd.org, owner-freebsd-fs@freebsd.org
References: <20180827154727.80f92fff9bbc931b37928d43@yamagi.org>
 <3c6f8c96-6ac9-7257-c8c0-8be2063a7c19@FreeBSD.org>
 <1c816966fbe698f0497df231139f9a05@ultra-secure.de>
From: Harry Schmalzbauer <freebsd@omnilan.de>
Organization: OmniLAN
Message-ID: <3530981a-7a44-6cf8-6fcd-3b44fd364cb7@omnilan.de>
Date: Wed, 29 Aug 2018 12:14:25 +0200
User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:52.0) Gecko/20100101
 Thunderbird/52.7.0
MIME-Version: 1.0
In-Reply-To: <1c816966fbe698f0497df231139f9a05@ultra-secure.de>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-US
X-Greylist: ACL 130 matched, not delayed by milter-greylist-4.2.7
 (mx0.gentlemail.de [78.138.80.130]); Wed, 29 Aug 2018 12:14:25 +0200 (CEST)
X-Milter: Spamilter (Reciever: mx0.gentlemail.de; Sender-ip: 78.138.80.135;
 Sender-helo: mh0.gentlemail.de; )
X-BeenThere: freebsd-fs@freebsd.org
X-Mailman-Version: 2.1.27
Precedence: list
List-Id: Filesystems <freebsd-fs.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-fs>,
 <mailto:freebsd-fs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-fs/>
List-Post: <mailto:freebsd-fs@freebsd.org>
List-Help: <mailto:freebsd-fs-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
 <mailto:freebsd-fs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 29 Aug 2018 10:14:27 -0000

Am 29.08.2018 um 11:45 schrieb rainer@ultra-secure.de:
> Am 2018-08-27 16:19, schrieb Lev Serebryakov:
>> On 27.08.2018 16:47, Yamagi Burmeister wrote:
>>
>>> With this program I was able to bisect the source and identify commit
>>> r321610 (MFV r318946: 8021 ARC buf data scatter-ization) as the 
>>> culprit:
>>> https://svnweb.freebsd.org/base?view=revision&revision=321610
>>  You could try to set "zfs_abd_scatter_enabled = 0" via kgdb and repeat
>> tests to be sure, that this code is a problem.
>>
>>  BTW, it is not clear, that FreeBSD needs this at all.
>
>
> Hi,
>
> how exactly do I do this?
>

Maybe this is more/easier applicaple for you:
https://svnweb.freebsd.org/changeset/base/338365

Can't really answer your question, but should help getting the desired 
result :-)

-harry