From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1ZsY7Q-0007pc-Od for user-mode-linux-devel@lists.sourceforge.net; Sat, 31 Oct 2015 15:31:00 +0000 Received: from a.ns.miles-group.at ([95.130.255.143] helo=radon.swed.at) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.76) id 1ZsY7P-0003Pn-Aq for user-mode-linux-devel@lists.sourceforge.net; Sat, 31 Oct 2015 15:31:00 +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> <1446305051.3238.13.camel@m3y3r.de> From: Richard Weinberger Message-ID: <5634DEAB.8090909@nod.at> Date: Sat, 31 Oct 2015 16:30:51 +0100 MIME-Version: 1.0 In-Reply-To: <1446305051.3238.13.camel@m3y3r.de> 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: Thomas Meyer , Anton Ivanov Cc: "user-mode-linux-devel@lists.sourceforge.net" Am 31.10.2015 um 16:24 schrieb Thomas Meyer: > Am Samstag, den 31.10.2015, 16:21 +0100 schrieb Richard Weinberger: >> Am 31.10.2015 um 16:16 schrieb Thomas Meyer: >>> mhh. strange. I didn't see this behaviour on my machine, but my >>> machine >>> is a rare single core system so, likely a race condition while >>> relaying >>> the timer interrupt to the userspace process. >> >> Here I can trigger it by starting UML, logging in and waiting ~5min. >> Then i try to run "top" --> top hangs forever. >> >>> But I'm out of ideas how this could happen! >> >> Maybe some stupid timeslice over/underflow. >> >>> what happens when you send the hanging process a SIGVTALRM signal? >>> does >>> it proceed correctly? >> >> You mean sending SIGVTALRM to the UML host process? > > No, to the hanging userspace process, maybe the uml host process did > receive a timer interrupt, but failed to relay this signal to the > correct userspace process. Well, this is not what top expects and dies. signal 26 (VTALRM) was caught by top, please see http://www.debian.org/Bugs/Reporting The problem is within UML's scheduler it does not wake top after the nanosleep() expires. Maybe the new clock is too imprecise, dunno. Thanks, //richard ------------------------------------------------------------------------------ _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel