2
edits
Changes
→[0.1] Optimize and run a benchmark program specifically designed to make use of glibc
== Project Contributor(s) ==
IRC:<br />
<ul><li>'''#ubuntu-arm''' (persia)<br /></li><li>'''#gentoo-embedded''' (solar and steev_)</li></ul> SENECA: '''Tae Hee (Tyler) Lee''' <blockquote>My fellow classmate, a great and helpful guy working on the [http://zenit.senecac.on.ca/wiki/index.php/To_Thumb_or_Not_to_Thumb To Thumb or Not to Thumb Project]. We both have the same project objective; to benchmark a system. (his project deals with 16-bit codes) We share access to the test builder cdot-beagleXM-0-3 and even ran tests both at the same time that could have toasted it! Tyler helped me out with with scripting/'makefiles' and using 'screen'.</blockquote>
== Project Details ==
'''What the project is all about'''
Currently, Fedora only supports armv5tel hardwarecodes. With the introduction release of armv7 architecture, (with beagleboardXM) Fedora-ARM is planning to upgrade pressed with the decision of upgrading its Fedora Universeto use armv7 code. While it seems logical, re-compiling the whole Fedora package is a strenuous task; therefore before . Before deciding to recompilethe whole universe, Fedora-ARM needs to make sure can test if optimizing certain system binaries to use armv7 architecture proves provides significant performance difference against the currently used armv5tel architecturecodes. The test would clarify if armv7 codes used for armv7 hardware really improves system performance.
This project aims for that sole purpose. By running a benchmark and compiler optimizationson system binaries, Fedora-ARM can contrast both technologies and use the results to decide if it's really worth to recompile the whole Fedora Universe to use armv7 architecture codes.
Below is a list of technologies by armv7.
'''rpm -q glibc'''<br />
<blockquote>glibc-2.11-2.fa3.armv5tel(Subjected for upgrade to armv7)</blockquote>
== Project Plan ==
*Dhrystone provides a more meaningful MIPS (Million Instructions Per Second) because results are compared to a reference machine.
*Dhrystone numbers reflect the performance of the C compiler and libraries more so than the performance of the processor itself. (considered as a weakness of the program)
*Check if armv7 optimization options and armv5tel optimization options differ significantly in system program performance boost
</blockquote>
[[Image:graph.png|thumb|450px|right| A graph showing the overall system performance of cdot-beagleXM-0-3]] '''Test Result(in DMIPS):'''<br /> Normal = 758.869322709 DMIPS<br />Optimized for armv5tel = 1034.82179852 DMIPS<br />Optimized for armv7 = 1034.82179852 DMIPS<br />
The benchmark graph shows that optimization increased the overall performance of cdot-beagleXM-0-3 by '''36%'''(Normal run vs. Optimized for armv5tel/armv7). The results for both armv5tel and armv7 optimizations are the same. (It can be assumed that the armv5tel glibc impacts the performance of C library dependent programs such as Dhrystone). Another possible reason is that the compiler used is already armv7 optimized (since dhrystone also relies on the compiler efficiency) The data gathered can be used as a reference for conducting 0.2 project release.<br /><br /><br /><br /><br /><br /><br /><br />
===[0.2] Install an armv7 glibc and re-run the benchmark using dhrystone===
Since optimizing the benchmark program using both architectures architecture optimizations revealed the same results, optimizing the system binaries and re-running the benchmark can should be able to provide a more concrete contrast between the 2 technologiesarchitectures.
The goal of this release is to find out if upgrading the armv5tel glibc would affect the performance of a C library dependent program such as dhrystone. By re-installing glibc using armv7 optimizations and re-running an armv7 optimized dhrystone; a better benchmark result is expected (Higher DMIPS). The result would be beneficial for Fedora-ARM, for it will help the community decide if armv5tel codes should continually be supported.
The Dhrystone (DMIPS) results never changed. The benchmark brought the same, exact number of DMIPS. Although Dhrystone does make use of C library functions and is assumed that the glibc would have effects on the program; the results proved that upgrading the glibc did not bring what's expected.
It is proven that armv7 and armv5 arch optimizations provide the same level of performance especially when running C library dependent programs on cdot-beagleXM-0-3 builder. Why is it possible when armv7 architecture is supposed to be better than armv5tel? One big answer is that the system tested currently is was built to use an [http://en.wikipedia.org/wiki/Application_binary_interface ABI] called "softfp". Although beagleboardXM (cortex-a8)supports the "hard floating-point" ABI, The Fedora-ARM currently can't afford to waste time to build building a system for supporting that supports "hardfp"solely on test purposes. To make things a little clearer, cdot-beagleXM-0-3 can't use the technology offered by ARM-cortex-a8 processor because of how the system (down to the lowest level) is built.
In conclusion, Fedora-ARM can continue to use armv5tel codes on armv7 machines. Deciding to recompile the whole universe for armv7 is somehow an inconvenient recommendation for now.
===[0.3]Thoughts for a future Future projectprospect===The previous test didn't leave an opportunity for me to work on [0.3] Release. Although the comparison is done, and the results are gathered; One last option to test armv7 technology still remains: "Rebuild everythingto use a hardfp ABI!" This recommendation would undoubtedly reveal the performance difference of armv7 against armv5tel; but at the same time would be a big project "not suitable for a single person to work on".
I hope that this project page including the [http://zenit.senecac.on.ca/wiki/index.php/Dhrystone_howto Dhrystone How To] page can be of use for future ARM based project reference.
== Project News ==
''December 16th, 2010'' - [0.2] and [0.3] Release updatedand finalized
''December 15th, 2010'' - Added the [http://zenit.senecac.on.ca/wiki/index.php/Dhrystone_howto Dhrystone How to Page]