Ming Lin <mlin@xxxxxxxxxx> writes: > On Mon, May 18, 2015 at 9:52 AM, Jeff Moyer <jmoyer@xxxxxxxxxx> wrote: >> Ming Lin <mlin@xxxxxxxxxx> writes: >> >>> diff --git a/block/blk-core.c b/block/blk-core.c >>> index fd154b9..909f317 100644 >>> --- a/block/blk-core.c >>> +++ b/block/blk-core.c >>> @@ -617,6 +617,10 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) >>> if (q->id < 0) >>> goto fail_q; >>> >>> + q->bio_split = bioset_create(4, 0); >>> + if (!q->bio_split) >>> + goto fail_id; >>> + >> >> Arbitrary numbers should be documented. > > Kent, > > Is there specific reason to choose number 4? > If no, I may change it to BIO_POOL_SIZE which is 2. Here's what he had to say last time around: On Mon, Nov 25, 2013 at 10:09:21PM -0800, Christoph Hellwig wrote: > > + q->bio_split = bioset_create(4, 0); > > + if (!q->bio_split) > > + goto fail_id; > > How did we arrive at a mempool size of 4 to make sure we can always make > progress with arbitrarily sized bios? Shouldn't we document the design > decision somewhere? It just has to be nonzero to guarantee forward progress - the bio_alloc_bioset() rescuer thing I did awhile back guarantees that. link: https://lkml.org/lkml/2013/11/26/47 Cheers, Jeff -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
