Andi Kleen wrote: > Yinghai Lu <[EMAIL PROTECTED]> writes: > >> we don't need copy too. already have x86_cpu_to_node_map > > That's a regression (probably from Mike's patches?). Until recently it was > used.
Yes, I had removed it because I couldn't find any references to it. And reading one's own percpu variables should be as efficient as reading one's own pda. But if I missed something, I apologize. Thanks for catching the problem. -Mike > > The reason the node number was put in there is that it generates far > shorter code to just fetch the local node number from the PDA than to > first go through a array lookup from the cpu number. It also saves a > costly cache line miss on the array if you're unlucky. > > It is far better to fix it than to remove it. > > I know Mike/Christoph want to get rid of the PDA and make per cpu data > as efficient as the PDA. If that happens the right fix is to create > a new per CPU data variable for the node number again. > > Here's a quick patch (tested on kvm with numa emulation only) > > It should be ok because PDA is set up early and > the early node is always 0 and there is a 0 in there > at early boot. > > Saves about 1.6k of text on a vmlinux here. > > Signed-off-by: Andi Kleen <[EMAIL PROTECTED]> > > Index: linux/include/asm-x86/topology.h > =================================================================== > --- linux.orig/include/asm-x86/topology.h > +++ linux/include/asm-x86/topology.h > @@ -34,11 +34,12 @@ > extern int cpu_to_node_map[]; > > #else > +#include <asm/pda.h> > DECLARE_PER_CPU(int, x86_cpu_to_node_map); > extern int x86_cpu_to_node_map_init[]; > extern void *x86_cpu_to_node_map_early_ptr; > /* Returns the number of the current Node. */ > -#define numa_node_id() > (early_cpu_to_node(raw_smp_processor_id())) > +#define numa_node_id() (read_pda(nodenumber)) > #endif > > extern cpumask_t node_to_cpumask_map[]; > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
