From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <43553B94.4070801@domain.hid> Date: Tue, 18 Oct 2005 20:14:44 +0200 From: Philippe Gerum MIME-Version: 1.0 Subject: Re: [Xenomai-core] Xenomai latency tests on various PowerPC boards References: <4354C0A9.5060901@domain.hid> <4354DB29.9060004@domain.hid> <4354E039.9010305@domain.hid> <4354E6A3.2010500@domain.hid> In-Reply-To: <4354E6A3.2010500@domain.hid> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wolfgang Grandegger Cc: xenomai@xenomai.org Wolfgang Grandegger wrote: > On 10/18/2005 01:44 PM Philippe Gerum wrote: > >>Philippe Gerum wrote: >> >>>Wolfgang Grandegger wrote: >>> >>> >>>>Hallo, >>>> >>>>attached you will find the results of Xemonai latency measurements on >>>>various embedded PowerPC boards using MPC 8xx and AMCC 4xx processors, >>>>from low to high end covering a worst case latency range from 25 to 225 >>>>us. It also includes a comparison with RTAI 3.0r5 on the slowest CPU. >>>>Here are some remarks and comments: >>>> >>>>- On low-end processor code size matters a lot and it's difficult to >>>> beat RTAI/RTHAL. >>>> >>> >>>Beat no, get closer, yes, probably. The good news is that looking at the >>>figures, we do have a margin of improvement! :o> >>> >>>Btw, the nucleus can be configured so that the user-space threading >>>engine is compiled out (i.e. CONFIG_XENO_OPT_PERVASIVE from the nucleus >>>menu), which would be the corresponding profile to compare with klatency >>>(i.e. sched_up). Disabling this option reduces the code size for the >>>nucleus from: >>> >>> text data bss dec hex filename >>> 66740 792 6540 74072 12158 >>>nucleus/xeno_nucleus.ko >>> >>>to: >>> >>> text data bss dec hex filename >>> 52596 576 3956 57128 df28 >>>nucleus/xeno_nucleus.ko >>> >> >>Disabling the periodic timer support which is unused for the klatency test >>brings this down to: >> >> text data bss dec hex filename >> 51040 544 3956 55540 d8f4 nucleus/xeno_nucleus.ko > > > OK, here are the new figures with (*) > > CONFIG_XENO_OPT_PERVASIVE is not set > CONFIG_XENO_HW_PERIODIC_TIMER is not set: > > |-----lat min|-----lat avg|-----lat max|-overrun|---test-time > RTAI 3.0r5 | 23120| 31838| 70520| ?| 00:12:26 > Xenomai | 50560| 98976| 199040| 0| 00:09:45 > Xenomai (*)| 44160| 96215| 200640| 0| 00:09:53 > > The min latency decreases as expected. > I just discovered that -00 did not include some recent changes I had in my tree, aimed at prevent high latencies during fork pressure. I've committed -01 which does include them. When time allows, I'd be interested to know if this has some impact on the Ocotea figures. TIA, -- Philippe.