On Tue, Aug 23, 2011 at 9:58 AM, Vaibhav Jain <vjoss197@xxxxxxxxx> wrote: > > > On Mon, Aug 22, 2011 at 10:11 PM, Vladimir Murzin <murzin.v@xxxxxxxxx> > wrote: >> >> On Tue, Aug 23, 2011 at 2:15 AM, Vaibhav Jain <vjoss197@xxxxxxxxx> wrote: >> > Hi, >> > Thanks for replying but I want to do this in a SMP machine. >> > Please help! >> > >> > Thanks >> > Vaibhav Jain >> > >> > On Wed, Aug 17, 2011 at 10:53 PM, Vladimir Murzin <murzin.v@xxxxxxxxx> >> > wrote: >> >> >> >> On Wed, Aug 17, 2011 at 11:01 PM, Vaibhav Jain <vjoss197@xxxxxxxxx> >> >> wrote: >> >> > Hi, >> >> > >> >> > I am looking into running a program on one of the cores which is >> >> > isolated >> >> > (logically offline ) >> >> > from the rest of the cores. I have come to that the command >> >> > echo 0 > /sys/device/system/cpu/<core num>/online >> >> > >> >> > will make a core logically offline, >> >> > What I need to do now is to run a program on this offline core. >> >> > Please >> >> > suggest on how to proceed. >> >> > >> >> > Thanks! >> >> > Vaibhav Jain >> >> > _______________________________________________ >> >> > Kernelnewbies mailing list >> >> > Kernelnewbies@xxxxxxxxxxxxxxxxx >> >> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> >> > >> >> > >> >> Hi Vaibhav, >> >> >> >> I think it's impossible to run out a process on unplugged CPU. May be >> >> AMP[1] is what you need, but it's a bit different approach. >> >> >> >> [1]http://en.wikipedia.org/wiki/Asymmetric_multiprocessing >> > >> > >> >> Hi Vaibhav, >> >> There is one more approach, but it's not operate on off-lined CPU. >> Have a look at isolcpu kernel boot option. >> Description in Documentation/kernel-parameters.txt says: >> >> This option can be used to specify one or more CPUs to isolate from >> the general SMP balancing and scheduling algorithms. You can move a >> process onto or off an "isolated" CPU via the CPU affinity syscalls or >> cpuset. <cpu number> begins at 0 and the maximum value is "number of >> CPUs in system - 1". This option is the preferred way to isolate CPUs. >> The alternative -- manually setting the CPU mask of all tasks in the >> system -- can cause problems and suboptimal load balancer performance. > > > > Hi, > > Thanks again! But I am asked to look into running process only when the cpu > has been logically offlined. > Someone suggested that I should make changes to arch/x_86/kernel/smpboot.c > file in one of the play_dead functions. But I don't know > what these function is doing and what changes should I make. Could you > please give me some idea ? > > > Thanks > Vaibhav Jain Good luck with that! _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
