On 9/11/2012 9:37 AM, Eric Keller wrote: > On Mon, Sep 10, 2012 at 12:07 PM, Kent A. Reed <[email protected]>wrote: > >> I will kick in the benchmarks I run on my BeagleBoardXM and ASUS >> AT5NM10-I while I wait. >> >> Have you set up a BeagleboardXM with a rt-preempt kernel? I have been > using a stock kernel on our BeagleboardXM's, I'm a little curious about > building and testing the rt-preempt kernel on them > Eric >
Hi, Eric. Short answer---no. When I said "run" I mean run the floating-point benchmark suites on a "stock" Linux kernel, just as Michael did. Long answer---I've been waiting on the RT PREEMPT crowd (don't ya love the lack of common nomenclature; the RT PREEMPT crowd is working with CONFIG_PREEMPT_RT). The sticking point seems to be the high-resolution timer. From their HOW_TO page (https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO) [apology in advance if page markup gets messed up] > The most default configurations here are ok as-they-are. However you > should make sure that you have > > * enable CONFIG_PREEMPT_RT > * activated the High-Resolution-Timer Option (Attention, the amount > of supported platforms by the HR timer is still very limited. > Right now the option is only supported on x86 systems, PowerPC and > ARM Support are however in queue.) > * disabled all Power Management Options like ACPI or APM (not all > ACPI functions are "bad", but you will have to check very > carefully to find out which function will affect your real time > system. Thus it's better to simply disable them all if you don't > need them. APM, however, is a no-go.) NOTE: Since rt patch > 2.6.18-rt6 you will probably have to activate ACPI option to > activate high resolution timer. Since the TSC timer on PC > platforms, as used in the previous versions, are now marked as > unsuitable for hrt mode due to many lacks of functionalities and > reliabilities, you will need i.E. pm_timer as provided by ACPI to > use as clock source. To activate the pm_timer, you can just > activate the ACPI_SUPPORT in menuconfig and deactivate all other > sub modules like "fan", "processor" or "button". If you have an > old pc, which lacks ACPI support, you might have problems using > the high resolution timer. > From another of their pages (https://rt.wiki.kernel.org/index.php/Frequently_Asked_Questions#What_sort_of_real-time_performance_should_I_expect.3F) > Which architectures does the CONFIG_PREEMPT_RT patch support? > There are systems representing the x86, x86_64, ARM, MIPS, and Power > architectures using the CONFIG_PREEMPT_RT patch. However, in many ways > this is the wrong question. Support for real-time is not just about > the instruction set architecture, but also about supporting the high > resolution timer provided by the CPU and/or CPU support chipset, the > device drivers for the system being well behaved, etc. So just because > an ARM system from company A may work quite well with the -rt > patchset, it does not guarantee that another ARM system from Company B > will work as well; it might have some longer latency problems or it > might not work at all. It is true that overall design and architecture > of the -rt patch tends to avoid the need for device-driver specific > changes, but there are always software bugs as well as hardware design > bugs. > Please refer toplatforms tested and in use with CONFIG_PREEMT_RT > <https://rt.wiki.kernel.org/index.php/CONFIG_PREEMPT_RT_Patch#Platforms_Tested_and_in_Use_with_CONFIG_PREEMPT_RT>section > > in this wiki for a list of platforms that members of the -rt community > have used successfully. The list is not exhaustive, of course, but it > should give a flavor of the sorts of packages that have had enjoyed > success using the -rt patch. There has been activity on the OMAP patching that is required in addition to the CONFIG_PREEMPT_RT patching (http://git.kernel.org/?p=linux/kernel/git/tmlind/linux-omap.git;a=summary). I just haven't had time to try out their work. I hope someone will shout out that I'm wrong and that all necessary patches are ready now for various popular ARM-based boards like BeagleBoard, BeagleBoardXM, BeagleBone, and Raspberry Pi. Regards, Kent ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
