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SubjectRe: Commit 34d76c41 causes linker errors on ia64 with NR_CPUS=4096

* Jiri Kosina <jkosina@suse.cz> wrote:

> On Tue, 20 Oct 2009, Ingo Molnar wrote:
>
> > > Commit 34d76c41 introduced percpu array update_shares_data, size of which
> > > being proportional to NR_CPUS. Unfortunately this blows up ia64 for large
> > > NR_CPUS configuration, as ia64 allows only 64k for .percpu section.
> > >
> > > Fix this by allocating this array dynamically and keep only pointer to it
> > > percpu.
> > >
> > > Signed-off-by: Jiri Kosina <jkosina@suse.cz>
> > > ---
> > > kernel/sched.c | 15 +++++++--------
> > > 1 files changed, 7 insertions(+), 8 deletions(-)
> >
> > Seems like an IA64 bug to me.
>
> IA64 guys actually use that as some kind of optimization for fast
> access to the percpu data in their pagefault handler, as far as I
> know.

Still looks like a bug if it causes a breakage (linker error) on IA64,
and if the 'fix' (i'd call it a workaround) causes a (small but nonzero)
performance regression on other architectures.

Ingo


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