From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1ZtB9v-0004lw-2e for user-mode-linux-devel@lists.sourceforge.net; Mon, 02 Nov 2015 09:12:11 +0000 Received: from a.ns.miles-group.at ([95.130.255.143] helo=radon.swed.at) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.76) id 1ZtB9u-0007VE-34 for user-mode-linux-devel@lists.sourceforge.net; Mon, 02 Nov 2015 09:12:11 +0000 References: <1445416947-824802-1-git-send-email-aivanov@brocade.com> <562D236E.7020108@kot-begemot.co.uk> <562DFC90.9030308@nod.at> <5631BB4E.4010301@kot-begemot.co.uk> <1446304232.3238.8.camel@m3y3r.de> <5634DAA4.70308@nod.at> <1446304594.3238.11.camel@m3y3r.de> <5634DC7B.3010707@nod.at> <56371B6D.3080506@kot-begemot.co.uk> <563720BA.20107@nod.at> <563721BB.10003@kot-begemot.co.uk> <56372439.2070509@nod.at> <5637257A.8000200@kot-begemot.co.uk> From: Richard Weinberger Message-ID: <563728E2.5090901@nod.at> Date: Mon, 2 Nov 2015 10:12:02 +0100 MIME-Version: 1.0 In-Reply-To: <5637257A.8000200@kot-begemot.co.uk> List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net Subject: Re: [uml-devel] [PATCH v3] um: Switch clocksource to hrtimers To: Anton Ivanov , Thomas Meyer Cc: "user-mode-linux-devel@lists.sourceforge.net" Am 02.11.2015 um 09:57 schrieb Anton Ivanov: > On 02/11/15 08:52, Richard Weinberger wrote: >> Am 02.11.2015 um 09:41 schrieb Anton Ivanov: >>> On 02/11/15 08:37, Richard Weinberger wrote: >>>> Hi! >>>> >>>> Am 02.11.2015 um 09:14 schrieb Anton Ivanov: >>>>> I was testing under similar conditions (CPU pinning using taskset -c 0 on a multicore). >>>>> >>>>> I have removed it and run some retests - I cannot reproduce the hang at this point with my config >>>>> >>>>> I am going to run a defconfig and compare the results to see if this will give me any insights on the root cause. >>>> I can reproduce on both my build machine (8 core) and my laptop (4 core). >>>> If it helps I can share the rootfs. >>>> >>>> On my laptop I was able to reproduce within 5 minutes. >>>> 1. make defconfig ARCH=um >>>> 2. make -j 4 linux ARCH=um >>>> 3. ./linux ubda=../Downloads/Debian-Squeeze-AMD64-root_fs mem=1G >>>> 4. login to tty0 >>>> 5. wait a few minutes >>>> 6. try to run top, it will hang in nanosleep >>> Pretty much the same. Does not hang, multiple test runs. Userspace is a relatively full install of a debian jessie. >>> >>> I ran deconfig and did a diff. The prime suspect differences between my config and defconfig are stack order 3 (not 1) and io sched of cfq, not deadline. >>> >>> I am going to retest just with these first to see if one of them is the culprit, if that does not make a difference, run it with defconfig and try to reproduce the hang. >> I'm pretty sure that you don't see the issue as your Jessy userspace uses nanosleep periodically. > > There are quite a few things running so this may indeed be the case. > > What do you use for userspace (so I can try to reproduce this and debug it)? Debian Squeeze amd64 with almost nothing running. PID TTY STAT TIME COMMAND 2 ? S 0:00 [kthreadd] 3 ? S 0:00 \_ [ksoftirqd/0] 4 ? S 0:00 \_ [kworker/0:0] 5 ? S< 0:00 \_ [kworker/0:0H] 6 ? S 0:00 \_ [kworker/u2:0] 7 ? S 0:00 \_ [kdevtmpfs] 8 ? S< 0:00 \_ [netns] 9 ? S< 0:00 \_ [writeback] 10 ? S 0:00 \_ [kworker/u2:1] 11 ? S< 0:00 \_ [crypto] 12 ? S 0:00 \_ [kworker/0:1] 13 ? S< 0:00 \_ [bioset] 14 ? S< 0:00 \_ [kblockd] 15 ? S 0:00 \_ [kswapd0] 68 ? S 0:00 \_ [fsnotify_mark] 221 ? S< 0:00 \_ [bioset] 229 ? S< 0:00 \_ [deferwq] 231 ? S 0:00 \_ [jbd2/ubda-8] 232 ? S< 0:00 \_ [ext4-rsv-conver] 233 ? S< 0:00 \_ [kworker/0:1H] 1 ? Ss 0:00 init [2] 271 ? S