dm io: use fixed initial mempool size
Replace the arbitrary calculation of an initial io struct mempool size
with a constant.
The code calculated the number of reserved structures based on the request
size and used a "magic" multiplication constant of 4. This patch changes
it to reserve a fixed number - itself still chosen quite arbitrarily.
Further testing might show if there is a better number to choose.
Note that if there is no memory pressure, we can still allocate an
arbitrary number of "struct io" structures. One structure is enough to
process the whole request.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 76a5af0..2067288 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -19,6 +19,8 @@
#define DM_MSG_PREFIX "io"
#define DM_IO_MAX_REGIONS BITS_PER_LONG
+#define MIN_IOS 16
+#define MIN_BIOS 16
struct dm_io_client {
mempool_t *pool;
@@ -41,33 +43,21 @@
static struct kmem_cache *_dm_io_cache;
/*
- * io contexts are only dynamically allocated for asynchronous
- * io. Since async io is likely to be the majority of io we'll
- * have the same number of io contexts as bios! (FIXME: must reduce this).
- */
-
-static unsigned int pages_to_ios(unsigned int pages)
-{
- return 4 * pages; /* too many ? */
-}
-
-/*
* Create a client with mempool and bioset.
*/
-struct dm_io_client *dm_io_client_create(unsigned num_pages)
+struct dm_io_client *dm_io_client_create(void)
{
- unsigned ios = pages_to_ios(num_pages);
struct dm_io_client *client;
client = kmalloc(sizeof(*client), GFP_KERNEL);
if (!client)
return ERR_PTR(-ENOMEM);
- client->pool = mempool_create_slab_pool(ios, _dm_io_cache);
+ client->pool = mempool_create_slab_pool(MIN_IOS, _dm_io_cache);
if (!client->pool)
goto bad;
- client->bios = bioset_create(16, 0);
+ client->bios = bioset_create(MIN_BIOS, 0);
if (!client->bios)
goto bad;
@@ -81,13 +71,6 @@
}
EXPORT_SYMBOL(dm_io_client_create);
-int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client)
-{
- return mempool_resize(client->pool, pages_to_ios(num_pages),
- GFP_KERNEL);
-}
-EXPORT_SYMBOL(dm_io_client_resize);
-
void dm_io_client_destroy(struct dm_io_client *client)
{
mempool_destroy(client->pool);
diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c
index 5dfbdcb..7196933 100644
--- a/drivers/md/dm-kcopyd.c
+++ b/drivers/md/dm-kcopyd.c
@@ -667,7 +667,7 @@
if (r)
goto bad_client_pages;
- kc->io_client = dm_io_client_create(min_pages);
+ kc->io_client = dm_io_client_create();
if (IS_ERR(kc->io_client)) {
r = PTR_ERR(kc->io_client);
goto bad_io_client;
diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index a1f3218..948e3f4 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -449,8 +449,7 @@
lc->io_req.mem.type = DM_IO_VMA;
lc->io_req.notify.fn = NULL;
- lc->io_req.client = dm_io_client_create(dm_div_up(buf_size,
- PAGE_SIZE));
+ lc->io_req.client = dm_io_client_create();
if (IS_ERR(lc->io_req.client)) {
r = PTR_ERR(lc->io_req.client);
DMWARN("couldn't allocate disk io client");
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 976ad46..53089aa 100644
--- 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_IO_PAGES 64
#define DM_KCOPYD_PAGES 64
#define DM_RAID1_HANDLE_ERRORS 0x01
@@ -887,7 +886,7 @@
return NULL;
}
- ms->io_client = dm_io_client_create(DM_IO_PAGES);
+ ms->io_client = dm_io_client_create();
if (IS_ERR(ms->io_client)) {
ti->error = "Error creating dm_io client";
mempool_destroy(ms->read_record_pool);
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index 95891df..135c2f1 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -154,11 +154,6 @@
struct workqueue_struct *metadata_wq;
};
-static unsigned sectors_to_pages(unsigned sectors)
-{
- return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9);
-}
-
static int alloc_area(struct pstore *ps)
{
int r = -ENOMEM;
@@ -318,8 +313,7 @@
chunk_size_supplied = 0;
}
- ps->io_client = dm_io_client_create(sectors_to_pages(ps->store->
- chunk_size));
+ ps->io_client = dm_io_client_create();
if (IS_ERR(ps->io_client))
return PTR_ERR(ps->io_client);
@@ -368,11 +362,6 @@
return r;
}
- r = dm_io_client_resize(sectors_to_pages(ps->store->chunk_size),
- ps->io_client);
- if (r)
- return r;
-
r = alloc_area(ps);
return r;