Hi Joel, If you look back through the kernel source history you can find a change that says the most CPUs that available on any [real] system that Linux works on is 32, so the value should max out at 32. The change didn't modify any other files of interest, so I imagine that changing the configuration to 64 should do the trick.
Ali On Mar 6, 2010, at 11:12 PM, Joel Hestness wrote: > 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 > <[email protected]> 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 > _______________________________________________ > m5-users mailing list > [email protected] > http://m5sim.org/cgi-bin/mailman/listinfo/m5-users _______________________________________________ m5-users mailing list [email protected] http://m5sim.org/cgi-bin/mailman/listinfo/m5-users
