diff options
| author | Paul Burton <paul.burton@imgtec.com> | 2017-02-23 02:44:53 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-02-23 03:41:29 +0300 |
| commit | b92df1de5d289c0b5d653e72414bf0850b8511e0 (patch) | |
| tree | 6604acfffcd8f9ca58499f892531bd08dc117fea /include | |
| parent | 7f354a548d1cb6bb01b6ee74aee9264aa152f1ec (diff) | |
| download | linux-b92df1de5d289c0b5d653e72414bf0850b8511e0.tar.xz | |
mm: page_alloc: skip over regions of invalid pfns where possible
When using a sparse memory model memmap_init_zone() when invoked with
the MEMMAP_EARLY context will skip over pages which aren't valid - ie.
which aren't in a populated region of the sparse memory map. However if
the memory map is extremely sparse then it can spend a long time
linearly checking each PFN in a large non-populated region of the memory
map & skipping it in turn.
When CONFIG_HAVE_MEMBLOCK_NODE_MAP is enabled, we have sufficient
information to quickly discover the next valid PFN given an invalid one
by searching through the list of memory regions & skipping forwards to
the first PFN covered by the memory region to the right of the
non-populated region. Implement this in order to speed up
memmap_init_zone() for systems with extremely sparse memory maps.
James said "I have tested this patch on a virtual model of a Samurai CPU
with a sparse memory map. The kernel boot time drops from 109 to
62 seconds. "
Link: http://lkml.kernel.org/r/20161125185518.29885-1-paul.burton@imgtec.com
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Tested-by: James Hartley <james.hartley@imgtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/memblock.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/memblock.h b/include/linux/memblock.h index 5b759c9acf97..38bcf00cbed3 100644 --- a/include/linux/memblock.h +++ b/include/linux/memblock.h @@ -203,6 +203,7 @@ 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); +unsigned long memblock_next_valid_pfn(unsigned long pfn, unsigned long max_pfn); /** * for_each_mem_pfn_range - early memory pfn range iterator |