On 06/07/2018 11:45, Thomas Gleixner wrote: >> One possibility is to introduce another layer of indirection: in >> addition to the percpu pvclock data, add a percpu pointer to the pvclock >> data and initialize it to point to a page-aligned variable in BSS. CPU0 >> (used by vDSO) doesn't touch the pointer and keeps using the BSS >> variable, APs instead redirect the pointer to the percpu data. > Yeah, thought about that, but the extra indirection is ugly. Instead of > using per cpu data, I just can allocate the memory _after_ the allocators > are up and running and use a single page sized static __initdata for the > early boot.
Either works for me. Assembly-wise, the indirection should be more or less the same as what we have now; even more efficient because it accesses a percpu pointer instead of computing it based on smp_processor_id(). Paolo