FOR REVIEW: New x86-64 vsyscall vgetcpu()
Zoltan Menyhart
Zoltan.Menyhart@bull.net
Fri Jun 16 15:36:00 GMT 2006
Andi Kleen wrote:
> That is not how user space TLS works. It usually has a base a register.
Can you please give me a real life (simplified) example?
> This means it cannot be cache colored (because you would need a static
> offset) and you couldn't share task_structs on a page.
I do not see the problem. Can you explain please?
E.g. the scheduler pulls a task instead of the current one. The CPU
will see "current->thread_info.cpu"-s of all the tasks at the same
offset anyway.
> Also you would make task_struct part of the userland ABI which
> seems like a very very bad idea to me. It means we couldn't change
> it anymore.
We can make some wrapper, e.g.:
user_per_cpu_var(name, offset)
"vgetcpu()" would also be added to the ABI which we couldn't change
easily either.
Thanks,
Zoltan
More information about the Libc-alpha
mailing list