From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4DA3FC97.10807@domain.hid> Date: Tue, 12 Apr 2011 09:17:43 +0200 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <20110409184122.GA11908@domain.hid> <20110409185503.GB11908@domain.hid> <4DA0B580.4070602@domain.hid> <4DA0B878.9010106@domain.hid> <20110410065250.GA28869@domain.hid> <4DA17996.3010103@domain.hid> <20110411171437.GA3715@domain.hid> <4DA37209.4000503@domain.hid> <20110412054348.GA2973@domain.hid> In-Reply-To: <20110412054348.GA2973@domain.hid> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-core] arm ixp: more trouble with recent xenomai List-Id: Xenomai life and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Cochran Cc: xenomai@xenomai.org Richard Cochran wrote: > On Mon, Apr 11, 2011 at 11:26:33PM +0200, Gilles Chanteperdrix wrote: >> Wait a minute. You are comparing results obtained after 2 or 3, or 10 >> minutes of runtime? I am not sure such results are meaningful. I do my >> benchmarks with the noltp_hell test: >> http://git.xenomai.org/?p=mkrootfs.git;a=blob_plain;f=tests/noltp_hell;hb=HEAD > > Of course, the longer the test, the more confidence you have. Not only that. The aim of the test is to trigger the worst case path. I suspect you can not trigger it with a 10 minutes tests. As you probably remember, I was once running Xenomai on IXP465, and the latency with Xenomai 2.4 and FCSE was around 150us. So, I suspect the test you show us are not really meaningful. Improving the worst case latency sometimes results in a higher average latency. Each release of the I-pipe patch is tested with the boards at my disposal, and the latency on the oldest board I have, a csb637, has been the same for a long time. But I can test again a 2.4.10 to confirm this. In any case, if you want to investigate the difference, the best tool is the I-pipe tracer. As I said, I am not sure it worked with all versions, but I can help get it working. > > But, when tracking down kernel freezes and toggling two component > versions and a half dozen CONFIG options, sometimes you do short tests > just to "sample" the combination. Exactly, and IMO, we should not get sidetracked in premature statements and conclusions about performance of the system when we are tracking a stability issue. Let us solve the stability issue first, then we will look into any potential performance issue, and we will do it with a proper load of the system, and with a four hours test. What compiler are you using by the way? -- Gilles.