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Commit 085ae065 authored by Jonathan Brassow's avatar Jonathan Brassow Committed by Alasdair G Kergon
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dm log userspace: group clear and mark requests 



Allow the device-mapper log's 'mark' and 'clear' requests to be
grouped and processed in a batch.  This can significantly reduce the
amount of traffic going between the kernel and userspace (where the
processing daemon resides).

Signed-off-by: default avatarJonathan Brassow <jbrassow@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 909cc4fb

drivers/md/dm-log-userspace-base.c

+79 −23
Original line number Diff line number Diff line
@@ -18,6 +18,14 @@ struct flush_entry { 
	struct list_head list;

};



/*

 * This limit on the number of mark and clear request is, to a degree,

 * arbitrary.  However, there is some basis for the choice in the limits

 * imposed on the size of data payload by dm-log-userspace-transfer.c:

 * dm_consult_userspace().

 */

#define MAX_FLUSH_GROUP_COUNT 32



struct log_c {

	struct dm_target *ti;

	uint32_t region_size;
@@ -348,6 +356,71 @@ static int userspace_in_sync(struct dm_dirty_log *log, region_t region, 
	return (r) ? 0 : (int)in_sync;

}



static int flush_one_by_one(struct log_c *lc, struct list_head *flush_list)

{

	int r = 0;

	struct flush_entry *fe;



	list_for_each_entry(fe, flush_list, list) {

		r = userspace_do_request(lc, lc->uuid, fe->type,

					 (char *)&fe->region,

					 sizeof(fe->region),

					 NULL, NULL);

		if (r)

			break;

	}



	return r;

}



static int flush_by_group(struct log_c *lc, struct list_head *flush_list)

{

	int r = 0;

	int count;

	uint32_t type = 0;

	struct flush_entry *fe, *tmp_fe;

	LIST_HEAD(tmp_list);

	uint64_t group[MAX_FLUSH_GROUP_COUNT];



	/*

	 * Group process the requests

	 */

	while (!list_empty(flush_list)) {

		count = 0;



		list_for_each_entry_safe(fe, tmp_fe, flush_list, list) {

			group[count] = fe->region;

			count++;



			list_del(&fe->list);

			list_add(&fe->list, &tmp_list);



			type = fe->type;

			if (count >= MAX_FLUSH_GROUP_COUNT)

				break;

		}



		r = userspace_do_request(lc, lc->uuid, type,

					 (char *)(group),

					 count * sizeof(uint64_t),

					 NULL, NULL);

		if (r) {

			/* Group send failed.  Attempt one-by-one. */

			list_splice_init(&tmp_list, flush_list);

			r = flush_one_by_one(lc, flush_list);

			break;

		}

	}



	/*

	 * Must collect flush_entrys that were successfully processed

	 * as a group so that they will be free'd by the caller.

	 */

	list_splice_init(&tmp_list, flush_list);



	return r;

}



/*

 * userspace_flush

 *
@@ -382,30 +455,13 @@ static int userspace_flush(struct dm_dirty_log *log) 
	if (list_empty(&mark_list) && list_empty(&clear_list))

		return 0;



	/*

	 * FIXME: Count up requests, group request types,

	 * allocate memory to stick all requests in and

	 * send to server in one go.  Failing the allocation,

	 * do it one by one.

	 */



	list_for_each_entry(fe, &mark_list, list) {

		r = userspace_do_request(lc, lc->uuid, fe->type,

					 (char *)&fe->region,

					 sizeof(fe->region),

					 NULL, NULL);

	r = flush_by_group(lc, &mark_list);

	if (r)

		goto fail;

	}



	list_for_each_entry(fe, &clear_list, list) {

		r = userspace_do_request(lc, lc->uuid, fe->type,

					 (char *)&fe->region,

					 sizeof(fe->region),

					 NULL, NULL);

	r = flush_by_group(lc, &clear_list);

	if (r)

		goto fail;

	}



	r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH,

				 NULL, 0, NULL, NULL);