Hi, It appears that I have fixed this issue by simply changing the range restriction on CONFIG_NR_CPUS from 2-32 to 2-64 cores in the file `./arch/alpha/Kconfig', and then setting CONFIG_NR_CPUS=64 in the file `.config.m5' before building. I would really appreciate if someone more familiar with M5 kernel modifications could verify that this is a valid correction and fix the M5 linux-patches repo to include this change. The affected versions of linux-2.6 are v2.6.22 and v2.6.27. Thanks, Joel
On Wed, Mar 3, 2010 at 3:50 PM, Joel Hestness <hestn...@cs.utexas.edu>wrote: > Hi, > I am running into an issue with running applications in ALPHA_FS on more > than 32 cores. The cores of index greater than or equal to 32 sit and spin, > as indicated by their uniformly small number of committed instructions, > during parallel sections of benchmarks with more than 32 threads. The > problem exists in kernel v2.6.27, which we built using the method described > on the M5 site. > I have done some testing, and I have identified that our kernels, v2.6.13 > and v2.3.16, both schedule threads on all 64 cores. Further, the file, > `.config.m5' contains a line to configure the maximum number of cores, which > is different for different linux versions: > > 2.6.13, 2.6.16: CONFIG_NR_CPUS=64 > 2.6.22, 2.6.27: CONFIG_NR_CPUS=32 > > I've tried building a few different versions, and each asks " Use M5 64 > Processor Tsumani Modification (BIG_TSUNAMI) [Y/n/?]", but setting this > doesn't seem to have an affect on kernels 2.6.22 or 2.6.27. The config > script restricts the CONFIG_NR_CPUS flag to 2-32 cores for kernel versions > 2.6.22 and 2.6.26. > Can someone give some insight into how to fix this so the v2.6.27 > scheduler works with 64 cores? > Thank you, > Joel > > -- > Joel Hestness > PhD Student, Computer Architecture > Dept. of Computer Science, University of Texas - Austin > http://www.cs.utexas.edu/~hestness > -- Joel Hestness PhD Student, Computer Architecture Dept. of Computer Science, University of Texas - Austin http://www.cs.utexas.edu/~hestness
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