Messages in this thread | | | From | Steven Cole <> | Subject | Re: UP 2.2.18 makes kernels 3% faster than UP 2.4.0-test12 | Date | Mon, 11 Dec 2000 16:02:27 -0700 |
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Aaron Tiensivu wrote: >Rerun the 2.4.0 with kgcc to be fair. :)
John Fremlin wrote: >Two points: (1) gcc 2.95 makes slightly slower code than egcs-1.1 >(according to benchmarks on gcc.gnu.org) so compile 2.4 kernel with >egcs for a fairer comparison. (2) The new VM was a performance
Ok, several people have said that kgcc makes a slightly better (faster) kernel than gcc. Here are some more results.
1 2 3 ave.
453 456 455 454.7 make bzImage for 2.4.0t12p7 running 2.4.0t12p7kgcc
compare this to my previous test using test12-pre7 compiled with gcc:
460 458 454 457.3 make bzImage for 2.4.0t12p7 running 2.4.0t12p7gcc
2.4.0t12p7kgcc is shorthand for 2.4.0-test12-pre7k made with kgcc. 2.4.0t12p7gcc is shorthand for 2.4.0-test12-pre7 made with gcc.
kgcc does indeed make a slightly faster (0.5%) kernel, but I think we're getting into the pregnant or dimpled chad thing at this point.
To create a kgcc test12-pre7, I modified line 18 and 29 of the top level Makefile to be =kgcc. Of course, I then restored the Makefile to original, since I'm not testing how fast gcc vs kgcc compiles a bunch of code. I modified EXTRAVERSION to be -test12k so I could double check with uname -r to make sure I booted the correct kernel.
Kgcc made a somewhat larger kernel than gcc. The same .config file was used for both kernels.
829034 Dec 7 20:46 vmlinuz-2.4.0-test12-pre7 854863 Dec 11 14:12 vmlinuz-2.4.0-test12-pre7k
I have a SMP (dual P-III 733Mhz) machine at work, but it will be unavailable for testing for a few more days. I suspect that 2.4.0-test12 will do better than 2.2.18 with 2 CPUs. I'll know in a few days.
Building kernels is something we do so frequently and this test is so easy to reproduce is why I performed it in the first place. I think it may be as good a test of real performance as some of the more formal benchmarks. Comments anyone?
Steven
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