Messages in this thread | | | Subject | Re: [PATCH] arm64: NUMA: Kconfig: Increase max number of nodes | From | Anshuman Khandual <> | Date | Wed, 21 Oct 2020 09:43:21 +0530 |
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On 10/20/2020 11:39 PM, Valentin Schneider wrote: > > Hi, > > Nit on the subject: this only increases the default, the max is still 2¹⁰.
Agreed.
> > On 20/10/20 18:34, Vanshidhar Konda wrote: >> The current arm64 max NUMA nodes default to 4. Today's arm64 systems can >> reach or exceed 16. Increase the number to 64 (matching x86_64). >> >> Signed-off-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com> >> --- >> arch/arm64/Kconfig | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >> index 893130ce1626..3e69d3c981be 100644 >> --- a/arch/arm64/Kconfig >> +++ b/arch/arm64/Kconfig >> @@ -980,7 +980,7 @@ config NUMA >> config NODES_SHIFT >> int "Maximum NUMA Nodes (as a power of 2)" >> range 1 10 >> - default "2" >> + default "6" > > This leads to more statically allocated memory for things like node to CPU > maps (see uses of MAX_NUMNODES), but that shouldn't be too much of an > issue.
The smaller systems should not be required to waste those memory in a default case, unless there is a real and available larger system with those increased nodes.
> > AIUI this also directly correlates to how many more page->flags bits are > required: are we sure the max 10 works on any aarch64 platform? I'm
We will have to test that. Besides 256 (2 ^ 8) is the first threshold to be crossed here.
> genuinely asking here, given that I'm mostly a stranger to the mm > world. The default should be something we're somewhat confident works > everywhere.
Agreed. Do we really need to match X86 right now ? Do we really have systems that has 64 nodes ? We should not increase the default node value and then try to solve some new problems, when there might not be any system which could even use that. I would suggest increase NODES_SHIFT value upto as required by a real and available system.
> >> depends on NEED_MULTIPLE_NODES >> help >> Specify the maximum number of NUMA Nodes available on the target >
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