From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-15?Q?Max_M=FCller?= Subject: Re: Tweak Latency on Intel ATOM Date: Tue, 16 Feb 2010 07:50:02 +0100 Message-ID: <4B7A401A.70902@gmx.net> References: <20100210163818.7f54ec3a@torg> <4B73B7B5.4070509@gmx.net> <20100211093447.3c0a97cd@torg> <4B7914C6.8080005@gmx.net> <20100215083847.1a4a7ef0@torg> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-rt-users@vger.kernel.org To: Clark Williams Return-path: Received: from mo-p05-ob.rzone.de ([81.169.146.182]:27840 "EHLO mo-p05-ob.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753576Ab0BPGuC (ORCPT ); Tue, 16 Feb 2010 01:50:02 -0500 In-Reply-To: <20100215083847.1a4a7ef0@torg> Sender: linux-rt-users-owner@vger.kernel.org List-ID: Clark Williams schrieb: > On Mon, 15 Feb 2010 10:32:54 +0100 > Max M=FCller wrote: > =20 > =20 >>> I'd say you're doing pretty good keeping under 50us. You might want= to >>> try it under a heavier load than the shell script you've been runni= ng. >>> If you don't want to fool with rteval, try kicking off a kernel com= pile >>> in another window like this: >>> >>> $ while true; do make -j4 clean bzImage modules; done >>> >>> and then run cyclictest. A kernel compile with parallel jobs (-j) i= s a >>> good overall load of computation and I/O. >>> >>> =20 >>> =20 >> I tested now like you told me with irqbalance and cpuspeed services=20 >> disabled. I hope i made the right for disabling irqbalance, i used t= he=20 >> kernel parameter acpi_no_irqbalance. Is this correct? Unfortunately = the=20 >> results were nearly equal as before. >> =20 > > I don't think you're going to get much better results on the Atom. I > have an MSI Nettop box with the dual-core version and I saw about the > same results as you. > > What sort of scheduling deadlines are you trying to meet?=20 > > Clark > =20 Shorter it is better it would be :-) I can also live with this results, but i wanted to make sure to get the= =20 best out of this hardware. Are you running both cores on the MSI box (maybe also with=20 hyperthreading enabled) with this results? In the meantime i thought also if the SMI (system management mode) coul= d=20 have a bad influence. I wrote a little userspace programm which=20 disables global SMI bit of the ICH7 southbridge. But also no better=20 results. After that i was told (thanks to Luis Claudio!) to check latency with=20 the kernel module hwlat_detector. The results of this module was 0. I=20 interpreted this that there is no SMI that causes the latency on my ATO= M=20 system. Regards, Max -- To unsubscribe from this list: send the line "unsubscribe linux-rt-user= s" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html