From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Yz8d0-0006CG-GM for user-mode-linux-devel@lists.sourceforge.net; Sun, 31 May 2015 19:10:34 +0000 Received: from ivanoab4.miniserver.com ([78.31.104.92]) by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:AES128-SHA:128) (Exim 4.76) id 1Yz8cz-0000UM-0m for user-mode-linux-devel@lists.sourceforge.net; Sun, 31 May 2015 19:10:34 +0000 Message-ID: <556B5CA0.9010200@kot-begemot.co.uk> Date: Sun, 31 May 2015 20:10:24 +0100 From: Anton Ivanov MIME-Version: 1.0 References: <556AED66.3030706@nod.at> <1433098827.8871.13.camel@m3y3r.de> In-Reply-To: <1433098827.8871.13.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] um: Switch clocksource to hrtimers To: Thomas Meyer Cc: user-mode-linux-devel@lists.sourceforge.net On 31/05/15 20:00, Thomas Meyer wrote: > Am Sonntag, den 31.05.2015, 13:15 +0200 schrieb Richard Weinberger: >> Am 20.05.2015 um 07:26 schrieb Thomas Meyer: >>> Am 20.05.2015 12:12 vorm. schrieb Richard Weinberger < >>> richard.weinberger@gmail.com>: >>>> On Sun, May 17, 2015 at 11:25 AM, Thomas Meyer >>>> wrote: >>>>> Switch the UML clocksource from interval timers to posix >>>>> interval timers >>>>> and move to a monotonic timer. >>>>> >>>>> This fixes suspend&resume related timer issues and improves >>>>> network >>>>> performance as TCP state machines are now fed with the correct >>>>> time; >>>>> also correct QoS and traffic shaping. >>>>> >>>>> Signed-off-by: Thomas Meyer >>>> What tree is this patch against? >>>> It does not clearly apply to Linus' tree. >>>> >>> Hi, >>> >>> I did tested the patch against 4.1-rc3-something; will update the >>> patch against the latest commit! > Hi, > >> Ping. >> Would be nice to have this patch for the 4.2 merge window. > I can provide you the current version of the patch, but I'm not sure if > it's ready for inclusion yet. Agree. > For example: > - With this patch I see new zombie processes of UML userspace > processes. I'm not sure what's going on here. +1 > - Anton reported some hang he sees with this patch I did not have a chance to work on it last week, will try to find some time this week. > - A person from cicso is worried about the potential idle CPU usage > after the patch, because of the many timers started, i.e. a host with > hundreds of UMLs. This is less then the old CPU usage - checking time and rearming nanosleeps and itimers is expensive. > > Also meanwhile I think is not the correct thing to start a new timer > for each UML userspace process, because the timer will also trigger the > userspace process, even the corresponding process isn't scheduled by > the kernel currently. I think the previous behaviour with the itimer > was okay, because the virtual timer only did execute when the process > was executing which is the correct thing to do for the currently active > task in the UML kernel. > I see two solutions for above problem: cascade the kernel timer into > the current active task; there is actually no need to start a timer in > each userspace process. > Start/stop each timer when a userspace process becomes active resp. > becomes inactive again. > I hope above logic makes some sense at all! What do you think about > this? Cascading the kernel timer looks like the correct solution. A. > > with kind regards > thomas > > > > ------------------------------------------------------------------------------ > _______________________________________________ > User-mode-linux-devel mailing list > User-mode-linux-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel > ------------------------------------------------------------------------------ _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel