This patch adds copy offload support to dm-kcopyd. If copy offload fails,
copying is performed using dm-io, just like before.
There is a module parameter "copy_offload" that can be set to enable or
disable this feature. It can be used to test performance of copy offload.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
---
drivers/md/dm-kcopyd.c | 38 +++++++++++++++++++++++++++++++++++++-
1 file changed, 37 insertions(+), 1 deletion(-)
Index: linux-3.16-rc5/drivers/md/dm-kcopyd.c
===================================================================
--- linux-3.16-rc5.orig/drivers/md/dm-kcopyd.c 2014-07-15 16:18:15.000000000 +0200
+++ linux-3.16-rc5/drivers/md/dm-kcopyd.c 2014-07-15 19:20:34.000000000 +0200
@@ -96,6 +96,9 @@ static DEFINE_SPINLOCK(throttle_spinlock
*/
#define MAX_SLEEPS 10
+static bool copy_offload = true;
+module_param(copy_offload, bool, S_IRUGO | S_IWUSR);
+
static void io_job_start(struct dm_kcopyd_throttle *t)
{
unsigned throttle, now, difference;
@@ -358,6 +361,8 @@ struct kcopyd_job {
sector_t progress;
struct kcopyd_job *master_job;
+
+ struct work_struct copy_work;
};
static struct kmem_cache *_job_cache;
@@ -709,6 +714,31 @@ static void submit_job(struct kcopyd_job
}
}
+static void copy_offload_work(struct work_struct *work)
+{
+ struct kcopyd_job *job = container_of(work, struct kcopyd_job, copy_work);
+ sector_t copied;
+
+ blkdev_issue_copy(job->source.bdev, job->source.sector,
+ job->dests[0].bdev, job->dests[0].sector,
+ job->source.count,
+ GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN,
+ NULL, NULL, &copied);
+
+ job->source.sector += copied;
+ job->source.count -= copied;
+ job->dests[0].sector += copied;
+ job->dests[0].count -= copied;
+
+ submit_job(job);
+}
+
+static void try_copy_offload(struct kcopyd_job *job)
+{
+ INIT_WORK(&job->copy_work, copy_offload_work);
+ queue_work(job->kc->kcopyd_wq, &job->copy_work);
+}
+
int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
unsigned int num_dests, struct dm_io_region *dests,
unsigned int flags, dm_kcopyd_notify_fn fn, void *context)
@@ -757,7 +787,13 @@ int dm_kcopyd_copy(struct dm_kcopyd_clie
job->context = context;
job->master_job = job;
- submit_job(job);
+ if (copy_offload && num_dests == 1 &&
+ bdev_copy_offload(job->source.bdev) &&
+ bdev_copy_offload(job->dests[0].bdev)) {
+ try_copy_offload(job);
+ } else {
+ submit_job(job);
+ }
return 0;
}
--
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