From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexey Fisher Subject: Re: less load less performance Date: Sun, 31 Oct 2010 20:44:27 +0100 Message-ID: <1288554267.31411.14.camel@zwerg> References: <1288543487.17727.29.camel@zwerg> <1288544473.7766.1.camel@pcjc2lap> <1288546826.18172.4.camel@zwerg> <20101031191843.GA9292@rhlx01.hs-esslingen.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail.gmx.net (mailout-de.gmx.net [213.165.64.23]) by gabe.freedesktop.org (Postfix) with SMTP id 59A5F9EEBD for ; Sun, 31 Oct 2010 12:44:34 -0700 (PDT) In-Reply-To: <20101031191843.GA9292@rhlx01.hs-esslingen.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Andreas Mohr Cc: "power@bughost.org" , "intel-gfx@lists.freedesktop.org" List-Id: intel-gfx@lists.freedesktop.org Am Sonntag, den 31.10.2010, 20:18 +0100 schrieb Andreas Mohr: > On Sun, Oct 31, 2010 at 06:40:26PM +0100, Alexey Fisher wrote: > > Am Sonntag, den 31.10.2010, 17:01 +0000 schrieb Peter Clifton: > > > On Sun, 2010-10-31 at 17:44 +0100, Alexey Fisher wrote: > > > > Hallo all, > > > > > > > > As i can understand if cpu do not get enough load it will work mostly in > > > > C4 mode and graphic perfome slow too. I think there is some thing wrong > > > > in this logic :) > > > > > > Yes, a little messed up.. try running your test at low screen-res with > > > this app running (once per core): > > > > > > int main( int argc, char **argv ) > > > { > > > while (1); > > > } > > > > > > (gcc loop.c -o loop) > > > > > > Do you get the high frames per second (non-full-screen) then? > > > > Yes! it working smooth, with 60fps (i have only single core atom with HT > > enabled) > > Why painfully compile a custom c app to keep the CPU busy? > > Boot with processor.max_cstate=1 > Much better performance? --> "BUG"! > ("BUG" == "something should probably be done about these power management side > effects") for some reasons "processor.max_cstate=1" do not make any difference, cpu still use C4. Interesting is maxcpus=1 do difference, C4 is used and it perform good too. So what can it be? Some SMP scheduler problem, IRQ balancing? I know intel CPUs had some PM problem, if 1 core is disabled it consume more power (may be no C4?). What talking against this theory: 1. if i start SMP and put one core off, this will make no difference so maxcpus=1 and "echo 0 > /sys/devices/system/cpu/cpu1/online" is not the same 2. i use Atom N280, there is only one core but HT is enabled. -- Regards, Alexey