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NVMe: Do not over allocate for discard requests

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Discard requests are often for very large ranges. The discard size is not
representative of the data transfer size so we don't need to allocate
for such a large prp list. This patch requests allocating only enough
for the memory needed for the data transfer and saves a little over 8k
of memory per max discard request.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Reported-by: Paul Grabinar <paul.grabinar@ranbarg.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Keith Busch 2014-10-06 15:23:06 -06:00 committed by Jens Axboe
parent 9e60352cf8
commit 9dbbfab7d5
1 changed files with 3 additions and 1 deletions
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4
drivers/block/nvme-core.c
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@ -763,11 +763,13 @@ static int nvme_submit_bio_queue(struct nvme_queue *nvmeq, struct nvme_ns *ns,
struct nvme_iod *iod;
int psegs = bio_phys_segments(ns->queue, bio);
int result;
unsigned size = !(bio->bi_rw & REQ_DISCARD) ? bio->bi_iter.bi_size :
sizeof(struct nvme_dsm_range);
if ((bio->bi_rw & REQ_FLUSH) && psegs)
return nvme_split_flush_data(nvmeq, bio);
iod = nvme_alloc_iod(psegs, bio->bi_iter.bi_size, ns->dev, GFP_ATOMIC);
iod = nvme_alloc_iod(psegs, size, ns->dev, GFP_ATOMIC);
if (!iod)
return -ENOMEM;