dm kcopyd: reserve fewer pages

Reserve just the minimum of pages needed to process one job.

Because we allocate pages from page allocator, we don't need to reserve
a large number of pages.  The maximum job size is SUB_JOB_SIZE and we
calculate the number of reserved pages based on this.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c
index 7196933..579647f 100644 (file)
--- a/drivers/md/dm-kcopyd.c
+++ b/drivers/md/dm-kcopyd.c
@@ -30,6 +30,7 @@
 #define SUB_JOB_SIZE   128
 #define SPLIT_COUNT    8
 #define MIN_JOBS       8
+#define RESERVE_PAGES  (DIV_ROUND_UP(SUB_JOB_SIZE << SECTOR_SHIFT, PAGE_SIZE))
 
 /*-----------------------------------------------------------------
  * Each kcopyd client has its own little pool of preallocated
@@ -636,8 +637,7 @@ int kcopyd_cancel(struct kcopyd_job *job, int block)
 /*-----------------------------------------------------------------
  * Client setup
  *---------------------------------------------------------------*/
-int dm_kcopyd_client_create(unsigned min_pages,
-                           struct dm_kcopyd_client **result)
+int dm_kcopyd_client_create(struct dm_kcopyd_client **result)
 {
        int r = -ENOMEM;
        struct dm_kcopyd_client *kc;
@@ -663,7 +663,7 @@ int dm_kcopyd_client_create(unsigned min_pages,
 
        kc->pages = NULL;
        kc->nr_reserved_pages = kc->nr_free_pages = 0;
-       r = client_reserve_pages(kc, min_pages);
+       r = client_reserve_pages(kc, RESERVE_PAGES);
        if (r)
                goto bad_client_pages;
 

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 53089aa..9defad0 100644 (file)
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -22,7 +22,6 @@
 #define DM_MSG_PREFIX "raid1"
 
 #define MAX_RECOVERY 1 /* Maximum number of regions recovered in parallel. */
-#define DM_KCOPYD_PAGES 64
 
 #define DM_RAID1_HANDLE_ERRORS 0x01
 #define errors_handled(p)      ((p)->features & DM_RAID1_HANDLE_ERRORS)
@@ -1116,7 +1115,7 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
                goto err_destroy_wq;
        }
 
-       r = dm_kcopyd_client_create(DM_KCOPYD_PAGES, &ms->kcopyd_client);
+       r = dm_kcopyd_client_create(&ms->kcopyd_client);
        if (r)
                goto err_destroy_wq;
 

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index a2d3309..5a2296d 100644 (file)
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -39,11 +39,6 @@ static const char dm_snapshot_merge_target_name[] = "snapshot-merge";
  */
 #define SNAPSHOT_COPY_PRIORITY 2
 
-/*
- * Reserve 1MB for each snapshot initially (with minimum of 1 page).
- */
-#define SNAPSHOT_PAGES (((1UL << 20) >> PAGE_SHIFT) ? : 1)
-
 /*
  * The size of the mempool used to track chunks in use.
  */
@@ -1116,7 +1111,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
                goto bad_hash_tables;
        }
 
-       r = dm_kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client);
+       r = dm_kcopyd_client_create(&s->kcopyd_client);
        if (r) {
                ti->error = "Could not create kcopyd client";
                goto bad_kcopyd;

diff --git a/include/linux/dm-kcopyd.h b/include/linux/dm-kcopyd.h
index 5db2163..312513d 100644 (file)
--- a/include/linux/dm-kcopyd.h
+++ b/include/linux/dm-kcopyd.h
@@ -25,8 +25,7 @@
  * To use kcopyd you must first create a dm_kcopyd_client object.
  */
 struct dm_kcopyd_client;
-int dm_kcopyd_client_create(unsigned num_pages,
-                           struct dm_kcopyd_client **result);
+int dm_kcopyd_client_create(struct dm_kcopyd_client **result);
 void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc);
 
 /*