Messages in this thread | | | Date | Mon, 23 Mar 2009 12:56:32 -0400 | From | Mathieu Desnoyers <> | Subject | Re: cli/sti vs local_cmpxchg and local_add_return |
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* 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.
Mathieu
> josh > > test init > test results: time for baseline > number of loops: 20000 > total time: 1532 > -> baseline takes 0 cycles > test end > test results: time for locked cmpxchg > number of loops: 20000 > total time: 48052 > -> locked cmpxchg takes 2 cycles > test end > test results: time for non locked cmpxchg > number of loops: 20000 > total time: 29141 > -> non locked cmpxchg takes 1 cycles > test end > test results: time for locked add return > number of loops: 20000 > total time: 44985 > -> locked add return takes 2 cycles > test end > test results: time for non locked add return > number of loops: 20000 > total time: 32400 > -> non locked add return takes 1 cycles > test end > test results: time for enabling interrupts (STI) > number of loops: 20000 > total time: 65579 > -> enabling interrupts (STI) takes 3 cycles > test end > test results: time for disabling interrupts (CLI) > number of loops: 20000 > total time: 29135 > -> disabling interrupts (CLI) takes 1 cycles > test end > test results: time for disabling/enabling interrupts (STI/CLI) > number of loops: 20000 > total time: 173594 > -> enabling/disabling interrupts (STI/CLI) takes 8 cycles > test end > [jwboyer@localhost ~]$
-- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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