lkml.org 
[lkml]   [2021]   [Apr]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 1/4] percpu: factor out pcpu_check_block_hint()
    Date
    From: Roman Gushchin <guro@fb.com>

    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>
    ---
    mm/percpu.c | 30 +++++++++++++++++++++++-------
    1 file changed, 23 insertions(+), 7 deletions(-)

    diff --git a/mm/percpu.c b/mm/percpu.c
    index 61339b3d9337..5edc7bd88133 100644
    --- a/mm/percpu.c
    +++ b/mm/percpu.c
    @@ -306,6 +306,25 @@ static unsigned long pcpu_block_off_to_off(int index, int 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
    * @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;

    /*
    - * Check to see if the allocation can fit in the chunk's contig hint.
    - * This is an optimization to prevent scanning by assuming if it
    - * cannot fit in the global hint, there is memory pressure and creating
    - * a new chunk would happen soon.
    + * This is an optimization to prevent scanning by assuming if the
    + * allocation cannot fit in the global hint, there is memory pressure
    + * and creating a new chunk would happen soon.
    */
    - bit_off = ALIGN(chunk_md->contig_hint_start, align) -
    - chunk_md->contig_hint_start;
    - if (bit_off + alloc_bits > chunk_md->contig_hint)
    + if (!pcpu_check_block_hint(chunk_md, alloc_bits, align))
    return -1;

    bit_off = pcpu_next_hint(chunk_md, alloc_bits);
    --
    2.31.1.368.gbe11c130af-goog
    \
     
     \ /
      Last update: 2021-04-20 00:52    [W:4.062 / U:0.536 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site