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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: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Jonathan Brassow 2011-01-13 19:59:51 +00:00 committed by Alasdair G Kergon
parent 909cc4fb48
commit 085ae0651b
1 changed files with 79 additions and 23 deletions
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102
drivers/md/dm-log-userspace-base.c
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@ -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.
*/
r = flush_by_group(lc, &mark_list);
if (r)
goto fail;
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);
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);
if (r)
goto fail;
}
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);