On Wed, 2016-02-17 at 17:29 +0100, Christophe Leroy wrote: > > Le 16/02/2016 22:21, Scott Wood a écrit : > > On Thu, 2016-02-11 at 17:16 +0100, Christophe Leroy wrote: > > > This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture. > > > PPC32 doesn't have the PACA structure, so we use the task_info > > > structure to store the accounting data. > > > > > > In order to reuse on PPC32 the PPC64 functions, all u64 data has > > > been replaced by 'unsigned long' so that it is u32 on PPC32 and > > > u64 on PPC64 > > > > > > Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr> > > > --- > > > Changes in v3: unlike previous version of the patch that was inspired > > > from IA64 architecture, this new version tries to reuse as much as > > > possible the PPC64 implementation. > > > > > > PPC32 doesn't have PACA and past discusion on v2 version has shown > > > that it is not worth implementing a PACA in PPC32 architecture > > > (see below benh opinion) > > > > > > benh: PACA is actually a data structure and you really really don't want > > > it > > > on ppc32 :-) Having a register point to current works, having a register > > > point to per-cpu data instead works too (ie, change what we do today), > > > but don't introduce a PACA *please* :-) > > And Ben never replied to my reply at the time: > > > > "What is special about 64-bit that warrants doing things differently from > > 32 > > -bit? What is the difference between PACA and "per-cpu data", other than > > the > > obscure name?" > > > > I can understand wanting to avoid churn, but other than that, doing things > > differently on 64-bit versus 32-bit sucks. > > > > What I can see is that PACA is always available via register r13. Do we > have anything equivalent on PPC32 ?
Just current in r2, which is the task_struct, not a task-independent per-cpu area. > If we define a per-cpu data for accounting, what will be the quick way > to get access to it in entry_32.S ? > Something like a table of accounting data for each CPU, that we index > with thread_info->cpu ? > This would allow a quite quick access, is it the good way to proceed in > order to have something closer to PPC64 ? Possibly. -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
