Messages in this thread | | | Date | Mon, 23 Mar 2009 13:04:18 -0400 | From | Josh Boyer <> | Subject | Re: cli/sti vs local_cmpxchg and local_add_return |
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On Mon, Mar 23, 2009 at 12:56:32PM -0400, Mathieu Desnoyers wrote: >* Josh Boyer (jwboyer@linux.vnet.ibm.com) wrote: >> On Mon, Mar 16, 2009 at 09:32:20PM -0400, Mathieu Desnoyers wrote: >> >Hi, >> > >> >I am trying to get access to some non-x86 hardware to run some atomic >> >primitive benchmarks for a paper on LTTng I am preparing. That should be >> >useful to argue about performance benefit of per-cpu atomic operations >> >vs interrupt disabling. I would like to run the following benchmark >> >module on CONFIG_SMP : >> > >> >- PowerPC >> >- MIPS >> >- ia64 >> >- alpha >> > >> >usage : >> >make >> >insmod test-cmpxchg-nolock.ko >> >insmod: error inserting 'test-cmpxchg-nolock.ko': -1 Resource temporarily unavailable >> >dmesg (see dmesg output) >> > >> >If some of you would be kind enough to run my test module provided below >> >and provide the results of these tests on a recent kernel (2.6.26~2.6.29 >> >should be good) along with their cpuinfo, I would greatly appreciate. >> > >> >Here are the CAS results for various Intel-based architectures : >> > >> >Architecture | Speedup | CAS | Interrupts | >> > | (cli + sti) / local cmpxchg | local | sync | Enable (sti) | Disable (cli) >> >------------------------------------------------------------------------------------------------- >> >Intel Pentium 4 | 5.24 | 25 | 81 | 70 | 61 | >> >AMD Athlon(tm)64 X2 | 4.57 | 7 | 17 | 17 | 15 | >> >Intel Core2 | 6.33 | 6 | 30 | 20 | 18 | >> >Intel Xeon E5405 | 5.25 | 8 | 24 | 20 | 22 | >> >> >> I know you have results from a POWER6 machine already, but >> here are the results on a dual-G5 running 2.6.29-rc7-git4. >> >> If you are interested, I could get you results from running >> this on an embedded PowerPC board. >> > >Thanks for the results. Well, those already shows that the tradeoff is >different between POWER6 and POWER5, so I guess further powerpc numbers >won't be required.
Correction, a dual-G5 is a PowerPC 970 machine. It's closer to POWER4 than POWER5 and nothing like POWER6. The Apple G5 machines are about 2 generations old in terms of 64-bit PowerPC CPUs.
josh
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