On Friday 16 June 2006 14:36, Zoltan Menyhart wrote: > Just to make sure I understand it correctly... > Assuming I have allocated per CPU data (numa control, etc.) pointed at by: > > void *per_cpu[MAXCPUS]; That is not how user space TLS works. It usually has a base a register. > > Assuming a per CPU variable has got an "offset" in each per CPU data area. > Accessing this variable can be done as follows: > > err = vgetcpu(&my_cpu, ...); > if (err) > goto .... > pointer = (typeof pointer) (per_cpu[my_cpu] + offset); > // use "pointer"... > > It is hundred times more long than "__get_per_cpu(var)++". 14 cycles is not a 100 times longer. > My idea is to map the current task structure at an arch. dependent > virtual address into the user space (obviously in RO). > > #define current ((struct task_struct *) 0x...) This means it cannot be cache colored (because you would need a static offset) and you couldn't share task_structs on a page. 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. -Andi - : send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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