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| author |   Dennis Zhou <dennis@kernel.org> | 2019-02-25 13:41:45 -0800 |
|---|---|---|
| committer | Dennis Zhou <dennis@kernel.org> | 2019-03-13 12:25:31 -0700 |
| commit | 382b88e961c7a4196e01cef3249297583d02d608 (patch) | |
| tree | 0d1dc78b084265547ec2531b42c6cb3a59a8340e /mm/percpu-internal.h | |
| parent | percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZE (diff) | |
| download | linux-dev-382b88e961c7a4196e01cef3249297583d02d608.tar.xz linux-dev-382b88e961c7a4196e01cef3249297583d02d608.zip | |
percpu: add block level scan_hint
Fragmentation can cause both blocks and chunks to have an early
first_firee bit available, but only able to satisfy allocations much
later on. This patch introduces a scan_hint to help mitigate some
unnecessary scanning.
The scan_hint remembers the largest area prior to the contig_hint. If
the contig_hint == scan_hint, then scan_hint_start > contig_hint_start.
This is necessary for scan_hint discovery when refreshing a block.
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Diffstat (limited to 'mm/percpu-internal.h')
| -rw-r--r-- | mm/percpu-internal.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/mm/percpu-internal.h b/mm/percpu-internal.h index b1739dc06b73..ec58b244545d 100644 --- a/mm/percpu-internal.h +++ b/mm/percpu-internal.h @@ -9,8 +9,17 @@ * pcpu_block_md is the metadata block struct. * Each chunk's bitmap is split into a number of full blocks. * All units are in terms of bits. + * + * The scan hint is the largest known contiguous area before the contig hint. + * It is not necessarily the actual largest contig hint though. There is an + * invariant that the scan_hint_start > contig_hint_start iff + * scan_hint == contig_hint. This is necessary because when scanning forward, + * we don't know if a new contig hint would be better than the current one. */ struct pcpu_block_md { + int scan_hint; /* scan hint for block */ + int scan_hint_start; /* block relative starting + position of the scan hint */ int contig_hint; /* contig hint for block */ int contig_hint_start; /* block relative starting position of the contig hint */ |