From owner-freebsd-current@freebsd.org  Sat Dec  8 19:09:47 2018
Return-Path: <owner-freebsd-current@freebsd.org>
Delivered-To: freebsd-current@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 3F6481326717;
 Sat,  8 Dec 2018 19:09:47 +0000 (UTC) (envelope-from lev@FreeBSD.org)
Received: from onlyone.not-for.work (onlyone.not-for.work
 [IPv6:2a01:4f8:201:6350::2])
 by mx1.freebsd.org (Postfix) with ESMTP id 8C56B8BE45;
 Sat,  8 Dec 2018 19:09:46 +0000 (UTC) (envelope-from lev@FreeBSD.org)
Received: from lion.home.serebryakov.spb.ru (unknown
 [IPv6:2001:470:923f:1:2830:b347:cdce:35cc])
 (Authenticated sender: lev@serebryakov.spb.ru)
 by onlyone.not-for.work (Postfix) with ESMTPSA id 87ADA3D84;
 Sat,  8 Dec 2018 22:09:44 +0300 (MSK)
Date: Sat, 8 Dec 2018 22:09:43 +0300
From: Lev Serebryakov <lev@FreeBSD.org>
Reply-To: lev@FreeBSD.org
Organization: FreeBSD
Message-ID: <1102394497.20181208220943@serebryakov.spb.ru>
To: Mateusz Guzik <mjguzik@gmail.com>
CC: freebsd-hackers@freebsd.org, freebsd-current@freebsd.org
Subject: ZFS sends TIRMs to agressively? (Was: Painfully slow compilation
 (read: "make buildworld buildkernel") on not-so-weak system)
In-Reply-To: <1844304999.20181208195837@serebryakov.spb.ru>
References: <902729965.20181208141303@serebryakov.spb.ru>  
 <1034207210.20181208172042@serebryakov.spb.ru>
 <CAGudoHFz3e3g2VYq0UMnaoh45UULBh0ch0P_1FHmGuF+0U7nhQ@mail.gmail.com>
 <1844304999.20181208195837@serebryakov.spb.ru>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Rspamd-Queue-Id: 8C56B8BE45
X-Spamd-Result: default: False [-2.99 / 15.00];
 local_wl_from(0.00)[FreeBSD.org];
 NEURAL_HAM_MEDIUM(-1.00)[-0.999,0];
 NEURAL_HAM_SHORT(-0.99)[-0.992,0];
 NEURAL_HAM_LONG(-1.00)[-0.999,0];
 ASN(0.00)[asn:24940, ipnet:2a01:4f8::/29, country:DE]
X-Rspamd-Server: mx1.freebsd.org
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
 <freebsd-current.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-current>, 
 <mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current/>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-current>, 
 <mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 08 Dec 2018 19:09:47 -0000

Hello Lev,

Saturday, December 8, 2018, 7:58:37 PM, you wrote:

>> Can you please narrow the problem down to a specific kernel revision?
>  I'm still not sure it is software or hardware problem.
 Looks like Samsung 850 EVO doesn't like TRIMs sent by ZFS (and I've thought
it is good SSD, consumer-grade, but really good one!).

 I've tuned down TRIMs with

vfs.zfs.per_txg_dirty_frees_percent=10
vfs.zfs.free_max_blocks=1000
vfs.zfs.vdev.trim_max_active=4

And it MOSTLY solved problem: there are some freezing from time to time (and
strange consumption of CPU by low-profile threads) with these settings.

 When I've disabled TRIM completely all freezes are gone, and low-profile
threads consume tenths of percent of CPU, as it is intended.

-- 
Best regards,
 Lev                            mailto:lev@FreeBSD.org