[dm-devel] [PATCH] dm log userspace: split flush_entry_pool to be per dirty-log [was: Re: mempool.c: Replace io_schedule_timeout with io_schedule]
Mike Snitzer
snitzer at redhat.com
Thu Feb 12 20:46:36 UTC 2015
On Fri, Dec 19 2014 at 2:53pm -0500,
Mike Snitzer <snitzer at redhat.com> wrote:
> On Thu, Dec 18 2014 at 10:37am -0500,
> Mike Snitzer <snitzer at redhat.com> wrote:
>
> > On Wed, Dec 17 2014 at 7:40pm -0500,
> > Timofey Titovets <nefelim4ag at gmail.com> wrote:
> >
> > > io_schedule_timeout(5*HZ);
> > > Introduced for avoidance dm bug:
> > > http://linux.derkeiler.com/Mailing-Lists/Kernel/2006-08/msg04869.html
> > > According to description must be replaced with io_schedule()
...
> > So I'll have to read the thread you linked to to understand if DM raid1
> > (or DM core) still suffers from the problem that this hack papered over.
>
> Heinz also pointed out that the primary issue that forced the use of
> io_schedule_timeout() was that dm-log-userspace (used by dm-raid1) makes
> use of a single shared mempool for multiple devices. Unfortunately,
> dm-log-userspace still has this shared mempool (flush_entry_pool). So
> we'll need to fix that up to be per-device before mm/mempool.c code can
> be switched to use io_schedule().
>
> I'll add this to my TODO. But it'll have to wait until after the new
> year.
I finally got around to this. Heinz and/or Jon, would you be willing to
test this? No real rush (won't go upstream until next merge window,
3.21). One question I have is: should FLUSH_ENTRY_POOL_SIZE be reduced
from 100 (previous default global min_nr) now that this reserve is
per-dirty-log?
From: Mike Snitzer <snitzer at redhat.com>
Date: Thu, 12 Feb 2015 15:20:35 -0500
Subject: [PATCH] dm log userspace: split flush_entry_pool to be per dirty-log
Use a single slab cache to allocate a mempool for each dirty-log.
This _should_ eliminate DM's need for io_schedule_timeout() in
mempool_alloc(); so io_schedule() should be sufficient now.
Also, rename struct flush_entry to dm_dirty_log_flush_entry to allow
KMEM_CACHE() to create a meaningful global name for the slab cache.
Also, eliminate some holes in struct log_c by rearranging members.
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
drivers/md/dm-log-userspace-base.c | 84 ++++++++++++++++++++------------------
1 file changed, 45 insertions(+), 39 deletions(-)
diff --git a/drivers/md/dm-log-userspace-base.c b/drivers/md/dm-log-userspace-base.c
index 03177ca..266bffc 100644
--- a/drivers/md/dm-log-userspace-base.c
+++ b/drivers/md/dm-log-userspace-base.c
@@ -17,7 +17,9 @@
#define DM_LOG_USERSPACE_VSN "1.3.0"
-struct flush_entry {
+#define FLUSH_ENTRY_POOL_SIZE 100
+
+struct dm_dirty_log_flush_entry {
int type;
region_t region;
struct list_head list;
@@ -34,22 +36,14 @@ struct flush_entry {
struct log_c {
struct dm_target *ti;
struct dm_dev *log_dev;
- uint32_t region_size;
- region_t region_count;
- uint64_t luid;
- char uuid[DM_UUID_LEN];
char *usr_argv_str;
uint32_t usr_argc;
- /*
- * in_sync_hint gets set when doing is_remote_recovering. It
- * represents the first region that needs recovery. IOW, the
- * first zero bit of sync_bits. This can be useful for to limit
- * traffic for calls like is_remote_recovering and get_resync_work,
- * but be take care in its use for anything else.
- */
- uint64_t in_sync_hint;
+ uint32_t region_size;
+ region_t region_count;
+ uint64_t luid;
+ char uuid[DM_UUID_LEN];
/*
* Mark and clear requests are held until a flush is issued
@@ -62,6 +56,15 @@ struct log_c {
struct list_head clear_list;
/*
+ * in_sync_hint gets set when doing is_remote_recovering. It
+ * represents the first region that needs recovery. IOW, the
+ * first zero bit of sync_bits. This can be useful for to limit
+ * traffic for calls like is_remote_recovering and get_resync_work,
+ * but be take care in its use for anything else.
+ */
+ uint64_t in_sync_hint;
+
+ /*
* Workqueue for flush of clear region requests.
*/
struct workqueue_struct *dmlog_wq;
@@ -72,19 +75,11 @@ struct log_c {
* Combine userspace flush and mark requests for efficiency.
*/
uint32_t integrated_flush;
-};
-
-static mempool_t *flush_entry_pool;
-static void *flush_entry_alloc(gfp_t gfp_mask, void *pool_data)
-{
- return kmalloc(sizeof(struct flush_entry), gfp_mask);
-}
+ mempool_t *flush_entry_pool;
+};
-static void flush_entry_free(void *element, void *pool_data)
-{
- kfree(element);
-}
+static struct kmem_cache *_flush_entry_cache;
static int userspace_do_request(struct log_c *lc, const char *uuid,
int request_type, char *data, size_t data_size,
@@ -254,6 +249,14 @@ static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
goto out;
}
+ lc->flush_entry_pool = mempool_create_slab_pool(FLUSH_ENTRY_POOL_SIZE,
+ _flush_entry_cache);
+ if (!lc->flush_entry_pool) {
+ DMERR("Failed to create flush_entry_pool");
+ r = -ENOMEM;
+ goto out;
+ }
+
/*
* Send table string and get back any opened device.
*/
@@ -310,6 +313,8 @@ static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
out:
kfree(devices_rdata);
if (r) {
+ if (lc->flush_entry_pool)
+ mempool_destroy(lc->flush_entry_pool);
kfree(lc);
kfree(ctr_str);
} else {
@@ -338,6 +343,8 @@ static void userspace_dtr(struct dm_dirty_log *log)
if (lc->log_dev)
dm_put_device(lc->ti, lc->log_dev);
+ mempool_destroy(lc->flush_entry_pool);
+
kfree(lc->usr_argv_str);
kfree(lc);
@@ -461,7 +468,7 @@ static int userspace_in_sync(struct dm_dirty_log *log, region_t region,
static int flush_one_by_one(struct log_c *lc, struct list_head *flush_list)
{
int r = 0;
- struct flush_entry *fe;
+ struct dm_dirty_log_flush_entry *fe;
list_for_each_entry(fe, flush_list, list) {
r = userspace_do_request(lc, lc->uuid, fe->type,
@@ -481,7 +488,7 @@ 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;
+ struct dm_dirty_log_flush_entry *fe, *tmp_fe;
LIST_HEAD(tmp_list);
uint64_t group[MAX_FLUSH_GROUP_COUNT];
@@ -563,7 +570,8 @@ static int userspace_flush(struct dm_dirty_log *log)
LIST_HEAD(clear_list);
int mark_list_is_empty;
int clear_list_is_empty;
- struct flush_entry *fe, *tmp_fe;
+ struct dm_dirty_log_flush_entry *fe, *tmp_fe;
+ mempool_t *flush_entry_pool = lc->flush_entry_pool;
spin_lock_irqsave(&lc->flush_lock, flags);
list_splice_init(&lc->mark_list, &mark_list);
@@ -643,10 +651,10 @@ static void userspace_mark_region(struct dm_dirty_log *log, region_t region)
{
unsigned long flags;
struct log_c *lc = log->context;
- struct flush_entry *fe;
+ struct dm_dirty_log_flush_entry *fe;
/* Wait for an allocation, but _never_ fail */
- fe = mempool_alloc(flush_entry_pool, GFP_NOIO);
+ fe = mempool_alloc(lc->flush_entry_pool, GFP_NOIO);
BUG_ON(!fe);
spin_lock_irqsave(&lc->flush_lock, flags);
@@ -672,7 +680,7 @@ static void userspace_clear_region(struct dm_dirty_log *log, region_t region)
{
unsigned long flags;
struct log_c *lc = log->context;
- struct flush_entry *fe;
+ struct dm_dirty_log_flush_entry *fe;
/*
* If we fail to allocate, we skip the clearing of
@@ -680,7 +688,7 @@ static void userspace_clear_region(struct dm_dirty_log *log, region_t region)
* to cause the region to be resync'ed when the
* device is activated next time.
*/
- fe = mempool_alloc(flush_entry_pool, GFP_ATOMIC);
+ fe = mempool_alloc(lc->flush_entry_pool, GFP_ATOMIC);
if (!fe) {
DMERR("Failed to allocate memory to clear region.");
return;
@@ -886,18 +894,16 @@ static int __init userspace_dirty_log_init(void)
{
int r = 0;
- flush_entry_pool = mempool_create(100, flush_entry_alloc,
- flush_entry_free, NULL);
-
- if (!flush_entry_pool) {
- DMWARN("Unable to create flush_entry_pool: No memory.");
+ _flush_entry_cache = KMEM_CACHE(dm_dirty_log_flush_entry, 0);
+ if (!_flush_entry_cache) {
+ DMWARN("Unable to create flush_entry_cache: No memory.");
return -ENOMEM;
}
r = dm_ulog_tfr_init();
if (r) {
DMWARN("Unable to initialize userspace log communications");
- mempool_destroy(flush_entry_pool);
+ kmem_cache_destroy(_flush_entry_cache);
return r;
}
@@ -905,7 +911,7 @@ static int __init userspace_dirty_log_init(void)
if (r) {
DMWARN("Couldn't register userspace dirty log type");
dm_ulog_tfr_exit();
- mempool_destroy(flush_entry_pool);
+ kmem_cache_destroy(_flush_entry_cache);
return r;
}
@@ -917,7 +923,7 @@ static void __exit userspace_dirty_log_exit(void)
{
dm_dirty_log_type_unregister(&_userspace_type);
dm_ulog_tfr_exit();
- mempool_destroy(flush_entry_pool);
+ kmem_cache_destroy(_flush_entry_cache);
DMINFO("version " DM_LOG_USERSPACE_VSN " unloaded");
return;
--
1.8.3.1
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