From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4DB6AB8E.2070000@domain.hid> Date: Tue, 26 Apr 2011 13:25:02 +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> <4DA192E0.2090802@domain.hid> <20110414164248.GA4725@domain.hid> <4DA846FF.5040204@domain.hid> <4DB11857.4030604@domain.hid> <4DB484C4.6040204@domain.hid> <20110425064852.GA3700@domain.hid> <4DB522F0.3090705@domain.hid> In-Reply-To: <4DB522F0.3090705@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 Gilles Chanteperdrix wrote: > Richard Cochran wrote: >> On Sun, Apr 24, 2011 at 10:15:00PM +0200, Gilles Chanteperdrix wrote: >>> some temporary results on the benchmark here: >>> http://www.xenomai.org/~gch/latency-at91sam9263.png >>> >>> The worst case latency seems not to vary much over time, it looks like >>> it is decreasing a bit, but the differences may well be in the >>> measurement noise. Unlocked context switch actually improves the latency. >>> >>> I will update the png as I get new results. >> Gilles, >> >> That is a very interesting graph. It might be nice to have a >> "performance benchmarks" page on the wiki, including that figure, plus >> the description of the test setup. I can contribute IXP and some >> PowerPC results. > > Yes, we should set this up. The xeno-test currently in the head branch > is made to help doing this. > >> Regarding the measured performance, the graphs are shaped like the >> letter, H (or like a Bactrian camel, with two humps). >> >> I appears to me that the peaks of the 2.4.10 lines (red, green) are >> standing clearly to the left of the 2.5.6 lines (blue, purple), by >> about 10 microseconds. I would say that 2.4.10 outperforms 2.5.6, on >> average. > > I added the average latencies (except for 2.4.10 with the I-pipe 1.14-04 > patch). The peak corresponds roughly to the average "lat max" column in > latency results. > > Both the I-pipe version and Xenomai version seem to contribute to the > increased average latency. > > The unlocked context switch also improves the worst-case at the expense > of the average. > > But there is hope, 2.6.33-1.18-03 introduces pic muting and re-enables > irq in the middle of gpio demuxing, which seems to improve the average > latency. Hi Richard, I jumped to conclusions too quickly. I am not sure the results I obtain really are meaningful. I am probably not doing it enough rigorously. Regards. -- Gilles.