NetBSD Problem Report #56309
From kardel@kardel.name Wed Jul 14 08:13:14 2021
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Message-Id: <20210714081200.56A15AAAC818@pip.kardel.name>
Date: Wed, 14 Jul 2021 10:12:00 +0200 (CEST)
From: kardel@netbsd.org
Reply-To: kardel@netbsd.org
To: gnats-bugs@NetBSD.org
Subject: swapctl -U is very inefficient (takes ages to eternities)
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>Number: 56309
>Category: kern
>Synopsis: swapctl -U is very inefficient (takes ages to eternities)
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: kern-bug-people
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Wed Jul 14 08:15:00 +0000 2021
>Last-Modified: Wed Jul 14 08:28:49 +0000 2021
>Originator: Frank Kardel
>Release: NetBSD 9.99.80 (also - .85 and likely beyond)
>Organization:
>Environment:
System: NetBSD pip 9.99.80 NetBSD 9.99.80 (PIPGEN) #0: Thu Feb 11 20:11:26 CET 2021 kardel@pip:/src/NetBSD/cur/src/obj.amd64/sys/arch/amd64/compile/PIPGEN amd64
Architecture: x86_64
Machine: amd64
>Description:
On a system with swap configured and swap having been used shutdown can
take a very long time when shutting down in the "Removing block-type swap devices"
phase. The read rate from the swap devices is very low for rust media and slow
for SSD media. swapctl -U picks up significant CPU time. The whole process takes
eternities for rust media and ages for SSDs.
Example (about 7 minutes into the shutdown):
0 12876 23709 25309 117 -20 19376 1656 - O< ? 6:18.30 swapctl -U -t blk
0 188 22490 84 117 0 17820 1400 tstile D+ pts/2 0:00.00 swapctl -l
On rust media the shutdown can take several hours. Even SSDs(NVME) can take several
tens of minutes.
>How-To-Repeat:
Use a system with swap enabled. Force the system to use swap space. Watch
a very long shutdown.
>Fix:
Workaround: set swapoff=NO in /etc/rc.conf.
>Release-Note:
>Audit-Trail:
>Unformatted:
(Contact us)
$NetBSD: query-full-pr,v 1.46 2020/01/03 16:35:01 leot Exp $
$NetBSD: gnats_config.sh,v 1.9 2014/08/02 14:16:04 spz Exp $
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