From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4F4E87C2.3070106@domain.hid> Date: Wed, 29 Feb 2012 21:17:06 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <4F4E630C.8020301@domain.hid> <4F4E680C.1000602@domain.hid> <4F4E712F.7050104@domain.hid> <4F4E8112.6060909@domain.hid> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] Execution time profiling List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Charles Lesire-Cabaniols Cc: xenomai@xenomai.org On 02/29/2012 08:59 PM, Charles Lesire-Cabaniols wrote: > 2012/2/29 Gilles Chanteperdrix > >> On 02/29/2012 08:44 PM, Charles Lesire-Cabaniols wrote: >>> 2012/2/29 Gilles Chanteperdrix >>> >>>> On 02/29/2012 07:03 PM, Charles Lesire-Cabaniols wrote: >>>>> 2012/2/29 Gilles Chanteperdrix >>>>> >>>>>> On 02/29/2012 06:52 PM, Charles Lesire-Cabaniols wrote: >>>>>>> 2012/2/29 Gilles Chanteperdrix >>>>>>> >>>>>>>> On 02/29/2012 06:29 PM, Charles Lesire-Cabaniols wrote: >>>>>>>>> Hi guys, >>>>>>>>> >>>>>>>>> I have installed a Debian+Xenomai (2.6.0) OS on my Gumstix Overo. >>>>>>>>> >>>>>>>>> I want to evaluate the execution time of a simple program, executed >>>> as >>>>>> a >>>>>>>>> real-time thread. >>>>>>>>> >>>>>>>>> I definitely wonder about which functions to use, as I have >>>> completely >>>>>>>>> inconsistent measures. >>>>>>>>> I have tried using rt_timer_read, rt_timer_tsc, clock_gettime. >>>>>>>>> I also directly read the CNNT register with ARM instructions (which >>>> is >>>>>>>> the >>>>>>>>> only one I think correct) in order to have a (good?) reference. >>>>>>>>> (...) >>>>>>>>> What am I doing wrong? >>>>>>>> >>>>>>>> So, you should printf("%Lu %Lu\n", rt_timer_read(), rt_timer_tsc()); >>>>>>>> >>>>>>>> Not printf("%lu", ...) >>>>>>>> >>>>>>>> -- >>>>>>>> Gilles. >>>>>>>> >>>>>>> >>>>>>> Effectively, that looks cleaner, thanks: >>>>>>> >>>>>>> ----- Xenomai rt_timer_read ----- >>>>>>> start: 49166276042 ; end: 49166432273 ; (s-e): 156231 ; CET: 156231 >>>>>>> ----- Xenomai rt_timer_tsc ----- >>>>>>> start: 639161547 ; end: 639163539 ; (s-e): 1992 ; CET: 1992 >>>>>>> ----- Xenomai clock_gettime ----- >>>>>>> [ s] start: 946684855 ; end: 946684855 ; (s-e): 0 ; CET: 0 >>>>>>> [ns] start: 275520245 ; end: 275677089 ; (s-e): 156844 ; CET: 156844 >>>>>>> >>>>>>> My ARM instruction reads 110554. >>>>>>> >>>>>>> Which Xenomai function should I use? >>>>>>> Which one is supposed to be the more accurate? >>>>>>> Does rt_timer_read return nsecs? >>>>>>> What is the unit of rt_timer_tsc? >>>>>> >>>>>> rt_timer_tsc uses whatever hardware counter is available, you need >>>>>> rt_timer_tsc2ns or rt_timer_ns2tsc to convert between this unit to and >>>>>> from nanoseconds. >>>>>> >>>>>> For more details, see: >>>>>> >>>>>> >>>>>> >>>> >> http://www.xenomai.org/documentation/xenomai-2.6/html/api/group__native__timer.html >>>>>> >>>>>> Depending on how xenomai user-space was compiled, rt_timer_tsc should >>>>>> have the lowest overhead. >>>>>> >>>>> >>>>> And are the default options the best ones? >>>> >>>> Yes, but I am not sure the debian package uses the default one. Please >>>> post here the disassembly of rt_timer_tsc, I will tell you if your >>>> system is compiled for the lowest overhead. >>>> >>>> >>> How to do that? >> >> arm-none-linux-objdump -d /path/to/libnative.so.3 | less >> search , when you find it, post the disassembly here. >> > > Here it is: > > 00005a54 : > 5a54: e59f2034 ldr r2, [pc, #52] ; 5a90 > > 5a58: e3e03a0f mvn r3, #61440 ; 0xf000 > 5a5c: e59f1030 ldr r1, [pc, #48] ; 5a94 > > 5a60: e08f2002 add r2, pc, r2 > 5a64: e5133003 ldr r3, [r3, #-3] > 5a68: e7921001 ldr r1, [r2, r1] > 5a6c: e59f0024 ldr r0, [pc, #36] ; 5a98 > > 5a70: e2833003 add r3, r3, #3 > 5a74: e0403283 sub r3, r0, r3, lsl #5 > 5a78: e92d4010 push {r4, lr} > 5a7c: e5910008 ldr r0, [r1, #8] > 5a80: e1a0e00f mov lr, pc > 5a84: e12fff13 bx r3 > 5a88: e8bd4010 pop {r4, lr} > 5a8c: e12fff1e bx lr > 5a90: 000086a4 andeq r8, r0, r4, lsr #13 > 5a94: 000000ec andeq r0, r0, ip, ror #1 > 5a98: ffff1004 undefined instruction 0xffff1004 This is the good one. -- Gilles.