> -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Dennis Zhou > Sent: 2019年2月28日 10:19 > To: Dennis Zhou <[email protected]>; Tejun Heo <[email protected]>; Christoph > Lameter <[email protected]> > Cc: Vlad Buslov <[email protected]>; [email protected]; > [email protected]; [email protected] > Subject: [PATCH 04/12] percpu: manage chunks based on contig_bits instead > of free_bytes > > When a chunk becomes fragmented, it can end up having a large number of > small allocation areas free. The free_bytes sorting of chunks leads to > unnecessary checking of chunks that cannot satisfy the allocation. > Switch to contig_bits sorting to prevent scanning chunks that may not be able > to service the allocation request. > > Signed-off-by: Dennis Zhou <[email protected]> > --- > mm/percpu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/percpu.c b/mm/percpu.c > index b40112b2fc59..c996bcffbb2a 100644 > --- a/mm/percpu.c > +++ b/mm/percpu.c > @@ -234,7 +234,7 @@ static int pcpu_chunk_slot(const struct pcpu_chunk > *chunk) > if (chunk->free_bytes < PCPU_MIN_ALLOC_SIZE || chunk->contig_bits > == 0) > return 0; > > - return pcpu_size_to_slot(chunk->free_bytes); > + return pcpu_size_to_slot(chunk->contig_bits * PCPU_MIN_ALLOC_SIZE); > } > > /* set the pointer to a chunk in a page struct */
Reviewed-by: Peng Fan <[email protected]> Not relevant to this patch, another optimization to percpu might be good to use per chunk spin_lock, not gobal pcpu_lock. Thanks, Peng. > -- > 2.17.1
