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percpu: factor out pcpu_check_block_hint()

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Factor out the pcpu_check_block_hint() helper, which will be useful
in the future. The new function checks if the allocation can likely
fit within the contig hint.

Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
This commit is contained in:
Roman Gushchin
2021-04-07 20:57:35 -07:00
committed by Dennis Zhou
parent 67c2669d69
commit 8ea2e1e35d
1 changed files with 23 additions and 7 deletions
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30
mm/percpu.c
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@@ -306,6 +306,25 @@ static unsigned long pcpu_block_off_to_off(int index, int off)
return index * PCPU_BITMAP_BLOCK_BITS + off; return index * PCPU_BITMAP_BLOCK_BITS + off;
} }
/**
* pcpu_check_block_hint - check against the contig hint
* @block: block of interest
* @bits: size of allocation
* @align: alignment of area (max PAGE_SIZE)
*
* Check to see if the allocation can fit in the block's contig hint.
* Note, a chunk uses the same hints as a block so this can also check against
* the chunk's contig hint.
*/
static bool pcpu_check_block_hint(struct pcpu_block_md *block, int bits,
size_t align)
{
int bit_off = ALIGN(block->contig_hint_start, align) -
block->contig_hint_start;
return bit_off + bits <= block->contig_hint;
}
/* /*
* pcpu_next_hint - determine which hint to use * pcpu_next_hint - determine which hint to use
* @block: block of interest * @block: block of interest
@@ -1066,14 +1085,11 @@ static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits,
int bit_off, bits, next_off; int bit_off, bits, next_off;
/* /*
* Check to see if the allocation can fit in the chunk's contig hint. * This is an optimization to prevent scanning by assuming if the
* This is an optimization to prevent scanning by assuming if it * allocation cannot fit in the global hint, there is memory pressure
* cannot fit in the global hint, there is memory pressure and creating * and creating a new chunk would happen soon.
* a new chunk would happen soon.
*/ */
bit_off = ALIGN(chunk_md->contig_hint_start, align) - if (!pcpu_check_block_hint(chunk_md, alloc_bits, align))
chunk_md->contig_hint_start;
if (bit_off + alloc_bits > chunk_md->contig_hint)
return -1; return -1;
bit_off = pcpu_next_hint(chunk_md, alloc_bits); bit_off = pcpu_next_hint(chunk_md, alloc_bits);