Messages in this thread | | | Subject | Re: 2.6 must-fix list, v2 | Date | Tue, 13 May 2003 23:46:21 +0100 | From | "Shaheed R. Haque" <> |
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Quoting Andrew Morton <akpm@digeo.com>:
> "Shaheed R. Haque" <srhaque@iee.org> wrote: > > > > - Add ability to restrict the the default CPU affinity mask so that > > sys_setaffinity() can be used to implement exclusive access to a CPU. > > Why is this useful?
Because it allows one to dedicate a CPU to a process. For example, lets say you have a quad processor,and want to run joe-random stuff on CPU 0, but a specialised program on CPUs 1, 2, 3 that does not want to compete with joe-random stuff.
With sys_setaffinity(), one can set the affinity of the special program to 0xe...but the default affinity for all the joe-random stuff is still 0xf (from cpu_online_map)! Since its impractical to to modify every single joe-random executable to set its affinity to 0x1, a way is needed to set the default. The logical place is in init(), a.k.a. kernel/fork.c.
I hope that make sense.
Thanks, Shaheed
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