Yes, the measurements are on no-load scenarios. I will try to repeat my measurements with system-loads as you suggest.
Following is the cpu-info of my board: ---------------------------------------------------------- Processor : ARM926EJ-S rev 5 (v5l) BogoMIPS : 131.48 Features : swp half fastmult edsp java CPU implementer : 0x41 CPU architecture: 5TEJ CPU variant : 0x0 CPU part : 0x926 CPU revision : 5 Cache type : write-back Cache clean : cp15 c7 ops Cache lockdown : format C Cache format : Harvard I size : 16384 I assoc : 4 I line length : 32 I sets : 128 D size : 16384 D assoc : 4 D line length : 32 D sets : 128 ---------------------------------------------------------- On Thu, Jun 24, 2010 at 5:20 PM, Gilles Chanteperdrix < gilles.chanteperd...@xenomai.org> wrote: > Nero Fernandez wrote: > > Thanks for your response, Philippe. > > > > The concerns while the carrying out my experiments were to: > > > > - compare xenomai co-kernel overheads (timer and context switch > latencies) > > in xenomai-space vs similar native-linux overheads. These are > > presented in > > the first two sheets. > > On what ARM system do you get these latency figures? I really doubt the > linux kernel has a bounded latency under 35us. Because: > - the preempt_rt people, which work on getting a bounded latency get > something around 200us on AT91, an ARM9; > - there would be no reason of the preempt_rt effort if the linux kernel > interrupt latency was already bounded. > > So, I take it that you do your measurement without generating a load. We > do our measurements using the latency test, while generating a load for > several hours. And on the average ARM, we usually get an interrupt > latency around 50us. > > Please add some load on the system, and do the measurments again. The > best source of load we have found so far is to load the LTP testsuite > while running the latency test. > > If you tell me what ARM SOC, or at least what ARM architecture revision > you use (the ARM920T core is an armv4, and the ARM926EJS is an armv5, so > ARM 9 does not tell us much), I can provide you with the root filesystem > we use for our tests. > > -- > Gilles. >
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