Re: [PATCH] mm: meminit: Finish initialisation of struct pages before basic setup

[Daniel J Blueman]

On Thu, May 14, 2015 at 6:03 PM, Daniel J Blueman 
<daniel@xxxxxxxxxxxxx> wrote:
> On Thu, May 14, 2015 at 12:31 AM, Mel Gorman <mgorman@xxxxxxx> wrote:
> > On Wed, May 13, 2015 at 10:53:33AM -0500, nzimmer wrote:
> > >  I am just noticed a hang on my largest box.
> > >  I can only reproduce with large core counts, if I turn down the
> > >  number of cpus it doesn't have an issue.
> >
> > Odd. The number of core counts should make little a difference as 
> > only
> > one CPU per node should be in use. Does sysrq+t give any indication 
> > how
> > or where it is hanging?
>
> I was seeing the same behaviour of 1000ms increasing to 5500ms [1]; 
> this suggests either lock contention or O(n) behaviour.
>
> Nathan, can you check with this ordering of patches from Andrew's 
> cache [2]? I was getting hanging until I a found them all.
>
> I'll follow up with timing data.

7TB over 216 NUMA nodes, 1728 cores, from kernel 4.0.4 load to login:

1. 2086s with patches 01-19 [1]

2. 2026s adding "Take into account that large system caches scale 
linearly with memory", which has:
min(2UL << (30 - PAGE_SHIFT), (pgdat->node_spanned_pages >> 3));

3. 2442s fixing to:
max(2UL << (30 - PAGE_SHIFT), (pgdat->node_spanned_pages >> 3));

4. 2064s adjusting minimum and shift to:
max(512UL << (20 - PAGE_SHIFT), (pgdat->node_spanned_pages >> 8));

5. 1934s adjusting minimum and shift to:
max(128UL << (20 - PAGE_SHIFT), (pgdat->node_spanned_pages >> 8));

6. 930s #5 with the non-temporal PMD init patch I had earlier proposed 
(I'll pursue separately)

The scaling patch isn't in -mm. #5 tests out nice on a bunch of other 
AMD systems, 64GB and up, so: Tested-by: Daniel J Blueman 
<daniel@xxxxxxxxxxxxx>.

Fine work, Mel!

Daniel

-- [1]

> http://ozlabs.org/~akpm/mmots/broken-out/memblock-introduce-a-for_each_reserved_mem_region-iterator.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-move-page-initialization-into-a-separate-function.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-only-set-page-reserved-in-the-memblock-region.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-pass-pfn-to-__free_pages_bootmem.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-make-__early_pfn_to_nid-smp-safe-and-introduce-meminit_pfn_in_nid.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-inline-some-helper-functions.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-inline-some-helper-functions-fix.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-initialise-a-subset-of-struct-pages-if-config_deferred_struct_page_init-is-set.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-initialise-remaining-struct-pages-in-parallel-with-kswapd.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-minimise-number-of-pfn-page-lookups-during-initialisation.patch
> http://ozlabs.org/~akpm/mmots/broken-out/x86-mm-enable-deferred-struct-page-initialisation-on-x86-64.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-free-pages-in-large-chunks-where-possible.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-reduce-number-of-times-pageblocks-are-set-during-struct-page-init.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-remove-mminit_verify_page_links.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-initialise-a-subset-of-struct-pages-if-config_deferred_struct_page_init-is-set-fix.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-finish-initialisation-of-struct-pages-before-basic-setup.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-finish-initialisation-of-struct-pages-before-basic-setup-fix.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-reduce-number-of-times-pageblocks-are-set-during-struct-page-init-fix.patch
> http://ozlabs.org/~akpm/mmots/broken-out/mm-meminit-inline-some-helper-functions-fix2.patch

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