From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4DFF84C0.6010008@domain.hid> Date: Mon, 20 Jun 2011 19:34:56 +0200 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <4DF9CA75.1040903@domain.hid> <4DF9DCE3.70703@domain.hid> <4DFBA463.3090902@domain.hid> <4DFBAEB9.8060106@domain.hid> <4DFBB08B.5020005@domain.hid> <4DFCC18F.3060207@domain.hid> <4DFF610F.5070602@domain.hid> <4DFF664C.5030504@domain.hid> <1308586589.2119.10.camel@domain.hid> In-Reply-To: <1308586589.2119.10.camel@domain.hid> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] Xenomai on i7-870 List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Philippe Gerum Cc: Xenomai help On 06/20/2011 06:16 PM, Philippe Gerum wrote: > On Mon, 2011-06-20 at 16:25 +0100, Jakub Nowacki wrote: >> On 06/20/2011 04:02 PM, Gilles Chanteperdrix wrote: >>> To make proper benchmarks, you should: >>> - let the latency run long >>> - provide some load, you can use the dohell script in xenomai-head to >>> generate the load. >>> >> I've generated a load using 'dd if=/dev/zero of=/dev/null' one for each >> core (8 in total), which is roughly the way how xeno-test does it. The >> test was running for 30 min, which is not very long but I should see the >> long latencies by that time, I think at least. >> >>> That said, having some spikes is not abnormal. The real question is to >>> know whether the latencies your get are sufficient for your application. >>> >> Well, I think it should be OK for peak latencies < 20 us, that is what >> I'm getting now. >> >>>> ioctl(RTTST_RTIOC_SWTEST_CREATE_KTASK): Cannot allocate memory >>> >>> You have to increase CONFIG_XENO_OPT_SYS_STACKPOOLSZ. >>> >> It is 128 Kb now. Should it be more? Is there any (thumb) rule for this >> value? > > Max # of concurrent kernel-based Xenomai threads x stack_size. 8k stack > minimum is a safe bet for x86_64. > > Typically, RTDM (driver) tasks in kernel space are Xenomai ones, so you > would need to reserve stack space for each of them in this amount. > > The switchtest driver is RTDM-based, and may run a number of RTDM tasks, > depending on the test scenario. The default scenario being to run 6 rtdm tasks by cpu (that would make 48 on an 8 cores processor). -- Gilles.