On 04/23/2015 05:23 AM, Mel Gorman wrote:
On Wed, Apr 22, 2015 at 04:45:00PM -0700, Andrew Morton wrote:
On Wed, 22 Apr 2015 18:07:50 +0100 Mel Gorman<mgorman@xxxxxxx> wrote:
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -32,6 +32,7 @@ config X86
select HAVE_UNSTABLE_SCHED_CLOCK
select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
select ARCH_SUPPORTS_INT128 if X86_64
+ select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT if X86_64&& NUMA
Put this in the "config X86_64" section and skip the "X86_64&&"?
Done.
Can we omit the whole defer_meminit= thing and permanently enable the
feature? That's simpler, provides better test coverage and is, we
hope, faster.
Yes. The intent was to have a workaround if there were any failures like
Waiman's vmalloc failures in an earlier version but they are bugs that
should be fixed.
And can this be used on non-NUMA? Presumably that won't speed things
up any if we're bandwidth limited but again it's simpler and provides
better coverage.
Nothing prevents it. There is less opportunity for parallelism but
improving coverage is desirable.
Memory access latency can be more than double for local vs. remote node
memory. Bandwidth can also be much lower depending on what kind of
interconnect is between the 2 nodes. So it is better to do it in a
NUMA-aware way. Within a NUMA node, however, we can split the memory
initialization to 2 or more local CPUs if the memory size is big enough.
Cheers,
Longman
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