On Thu, Aug 15, 2013 at 01:43:48PM -0700, Andrew Morton wrote:
> On Wed, 14 Aug 2013 22:46:29 -0700 Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
>
> > Current early_pfn_to_nid() on arch that support memblock go
> > over memblock.memory one by one, so will take too many try
> > near the end.
> >
> > We can use existing memblock_search to find the node id for
> > given pfn, that could save some time on bigger system that
> > have many entries memblock.memory array.
>
> Looks nice. I wonder how much difference it makes.
Here are the timing differences for several machines.
In each case with the patch less time was spent in __early_pfn_to_nid().
3.11-rc5 with patch difference (%)
-------- ---------- --------------
UV1: 256 nodes 9TB: 411.66 402.47 -9.19 (2.23%)
UV2: 255 nodes 16TB: 1141.02 1138.12 -2.90 (0.25%)
UV2: 64 nodes 2TB: 128.15 126.53 -1.62 (1.26%)
UV2: 32 nodes 2TB: 121.87 121.07 -0.80 (0.66%)
Time in seconds.
Acked-by: Russ Anderson <rja@xxxxxxx>
> > ...
> >
> > --- linux-2.6.orig/include/linux/memblock.h
> > +++ linux-2.6/include/linux/memblock.h
> > @@ -60,6 +60,8 @@ int memblock_reserve(phys_addr_t base, p
> > void memblock_trim_memory(phys_addr_t align);
> >
> > #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
> > +int memblock_search_pfn_nid(unsigned long pfn, unsigned long *start_pfn,
> > + unsigned long *end_pfn);
> > void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn,
> > unsigned long *out_end_pfn, int *out_nid);
> >
> > Index: linux-2.6/mm/memblock.c
> > ===================================================================
> > --- linux-2.6.orig/mm/memblock.c
> > +++ linux-2.6/mm/memblock.c
> > @@ -914,6 +914,24 @@ int __init_memblock memblock_is_memory(p
> > return memblock_search(&memblock.memory, addr) != -1;
> > }
> >
> > +#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
> > +int __init_memblock memblock_search_pfn_nid(unsigned long pfn,
> > + unsigned long *start_pfn, unsigned long *end_pfn)
> > +{
> > + struct memblock_type *type = &memblock.memory;
> > + int mid = memblock_search(type, (phys_addr_t)pfn << PAGE_SHIFT);
> > +
> > + if (mid == -1)
> > + return -1;
> > +
> > + *start_pfn = type->regions[mid].base >> PAGE_SHIFT;
> > + *end_pfn = (type->regions[mid].base + type->regions[mid].size)
> > + >> PAGE_SHIFT;
> > +
> > + return type->regions[mid].nid;
> > +}
> > +#endif
>
> This function will have no callers if
> CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID=y. That's not too bad as the
> function is __init_memblock. But this depends on
> CONFIG_ARCH_DISCARD_MEMBLOCK. Messy :(
>
--
Russ Anderson, OS RAS/Partitioning Project Lead
SGI - Silicon Graphics Inc rja@xxxxxxx
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