From owner-freebsd-performance@FreeBSD.ORG Sun Dec 18 07:52:50 2011 Return-Path: Delivered-To: freebsd-performance@FreeBSD.ORG Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D1ACA106564A; Sun, 18 Dec 2011 07:52:50 +0000 (UTC) (envelope-from ache@vniz.net) Received: from vniz.net (vniz.net [194.87.13.69]) by mx1.freebsd.org (Postfix) with ESMTP id 2AF108FC17; Sun, 18 Dec 2011 07:52:45 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by vniz.net (8.14.5/8.14.5) with ESMTP id pBI7qhPc045514; Sun, 18 Dec 2011 11:52:43 +0400 (MSK) (envelope-from ache@vniz.net) Received: (from ache@localhost) by localhost (8.14.5/8.14.5/Submit) id pBI7qgIB045513; Sun, 18 Dec 2011 11:52:42 +0400 (MSK) (envelope-from ache) Date: Sun, 18 Dec 2011 11:52:42 +0400 From: Andrey Chernov To: Ian Smith Message-ID: <20111218075241.GA45367@vniz.net> Mail-Followup-To: Andrey Chernov , Ian Smith , Bruce Cran , Ivan Klymenko , Doug Barton , "O. Hartmann" , Current FreeBSD , freebsd-stable@FreeBSD.ORG, freebsd-performance@FreeBSD.ORG References: <4EE1EAFE.3070408@m5p.com> <4EE22421.9060707@gmail.com> <4EE6060D.5060201@mail.zedat.fu-berlin.de> <4EE69C5A.3090005@FreeBSD.org> <20111213104048.40f3e3de@nonamehost.> <20111213090051.GA3339@vniz.net> <4EED5200.20302@cran.org.uk> <20111218164924.L64681@sola.nimnet.asn.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111218164924.L64681@sola.nimnet.asn.au> User-Agent: Mutt/1.5.21 (2010-09-15) Cc: Bruce Cran , Ivan Klymenko , Doug Barton , freebsd-stable@FreeBSD.ORG, "O. Hartmann" , Current FreeBSD , freebsd-performance@FreeBSD.ORG Subject: Re: SCHED_ULE should not be the default X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 18 Dec 2011 07:52:50 -0000 On Sun, Dec 18, 2011 at 05:51:47PM +1100, Ian Smith wrote: > On Sun, 18 Dec 2011 02:37:52 +0000, Bruce Cran wrote: > > On 13/12/2011 09:00, Andrey Chernov wrote: > > > I observe ULE interactivity slowness even on single core machine (Pentium > > > 4) in very visible places, like 'ps ax' output stucks in the middle by ~1 > > > second. When I switch back to SHED_4BSD, all slowness is gone. > > > > I'm also seeing problems with ULE on a dual-socket quad-core Xeon machine > > with 16 logical CPUs. If I run "tar xf somefile.tar" and "make -j16 > > buildworld" then logging into another console can take several seconds. > > Sometimes even the "Password:" prompt can take a couple of seconds to appear > > after typing my username. > > I'd resigned myself to expecting this sort of behaviour as 'normal' on > my single core 1133MHz PIII-M. As a reproducable data point, running > 'dd if=/dev/random of=/dev/null' in one konsole, specifically to heat > the CPU while testing my manual fan control script, hogs it up pretty > much while regularly running the script below in another konsole to > check values - which often gets stuck half way, occasionally pausing > _twice_ before finishing. Switching back to the first konsole (on > another desktop) to kill the dd can also take a couple/few seconds. This issue not about slow machine under load, because the same slow machine under exact the same load, but with SCHED_4BSD is very fast to response interactively. I think we should not misinterpret interactivity with speed. I see no big speed (i.e. compilation time) differences, switching schedulers, but see big _interactivity_ difference. ULE in general tends to underestimate interactive processes in favour of background ones. It perhaps helps to compilation, but looks like slowpoke OS from the interactive user experience. -- http://ache.vniz.net/