From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 24 Jan 2008 10:41:50 +0100 From: Juan Antonio Garcia Redondo Message-ID: <20080124094150.GA7503@domain.hid> References: <20080123065221.GB6573@domain.hid> <2ff1a98a0801230204s15e4eefaifdd2c946c44549df@domain.hid> <2ff1a98a0801230515i77f8c22bk866c4cd592a3a9b8@domain.hid> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2ff1a98a0801230515i77f8c22bk866c4cd592a3a9b8@domain.hid> Subject: Re: [Xenomai-help] AT91SAM9260 latency List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gilles Chanteperdrix Cc: jagarcia@domain.hid, xenomai@xenomai.org On 23/01/08 14:15, Gilles Chanteperdrix wrote: > On Jan 23, 2008 11:04 AM, Gilles Chanteperdrix > wrote: > > On Jan 23, 2008 7:52 AM, Juan Antonio Garcia Redondo > > > > wrote: > > > I see everything OK except for the first samples of cyclictests. Any comments ? > > > > The load you apply does not load the cache, which is a source of > > jitter. You should run the cache calibrator (I do not find the cache > > calibrator URL, but it is somewhere in Xenomai distribution or wiki). > > It is in the TROUBLESHOOTING guide, question "How do I adequately stress test". > > -- > Gilles Chanteperdrix Thanks Gilles, I've done more tests using the cache calibrator from http://www.cwi.nl/~manegold/Calibrator. The latency numbers are very similar althought I've found an strange behaviour related to telnet sessions. Environment: o Tests running from console over atmel serial port. o A telnet session over on-chip ethernet. o System without load. ./latency -p 500 -t0 == All results in microseconds warming up... RTT| 00:00:01 (periodic user-mode task, 500 us period, priority 99) RTH|-RTH----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst RTD| 49.613| 52.190| 62.822| 0| 49.613| 62.822 RTD| 42.203| 52.512| 66.365| 0| 42.203| 66.365 Now If hit a key on the telnet session : RTD| 36.726| 57.989| 109.536| 0| 31.572| 109.536 <-------- Here I've hit the key. RTD| 36.404| 51.868| 69.587| 0| 31.572| 109.536 RTD| 35.760| 51.868| 73.775| 0| 31.572| 109.536 Now, I launch an script which executes four instances of cache calibrator. RTD| 45.103| 57.667| 75.708| 0| 32.538| 122.422 RTD| 45.425| 57.023| 76.030| 0| 32.538| 122.422 RTD| 46.069| 57.023| 75.708| 0| 32.538| 122.422 Now, I can hit a key on the telnet session without effects over latency numbers: RTD| 44.136| 57.989| 75.386| 0| 27.384| 128.221 RTD| 46.713| 57.345| 76.353| 0| 27.384| 128.221 RTD| 44.780| 57.345| 76.675| 0| 27.384| 128.221 RTD| 43.492| 56.701| 76.997| 0| 27.384| 128.221 Now I stop the calibrator process and launch 'ping -f -s2048 192.168.2.82' from an external machine. RTD| 40.270| 68.621| 90.850| 0| 27.384| 128.221 RTD| 36.082| 68.621| 88.273| 0| 27.384| 128.221 RTD| 40.592| 67.976| 91.494| 0| 27.384| 128.221 RTD| 41.237| 68.298| 89.239| 0| 27.384| 128.221 Now If hit a key on the telnet session : RTD| 42.203| 67.976| 88.273| 0| 27.384| 128.221 RTD| 32.216| 93.427| 128.543| 0| 27.384| 128.543 <---------- Here I've hit the key. RTD| 42.203| 68.298| 87.628| 0| 27.384| 128.543 And again the calibrator execution results on eliminate the strange behaviour whith the telnet session. Any clues ? BTW, if finally the bad numbers on ARM are user-context switches related, are you considering the ipipe upgrading to 2.6.23 ? Regards, Juan Antonio