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authorMike Snitzer <snitzer@redhat.com>2013-09-12 18:06:12 -0400
committerMike Snitzer <snitzer@redhat.com>2013-09-23 10:42:24 -0400
commitf47908269fb53d522a956b78612a0037f5faf8e7 (patch)
tree47723023a5389daa5cdd974d4b53c3d91198be6e /drivers/md/dm.c
parent6cfa58573f9b4a543005baa002e137820504c7af (diff)
dm: add reserved_rq_based_ios module parameter
Allow user to change the number of IOs that are reserved by request-based DM's mempools by writing to this file: /sys/module/dm_mod/parameters/reserved_rq_based_ios The default value is RESERVED_REQUEST_BASED_IOS (256). The maximum allowed value is RESERVED_MAX_IOS (1024). Export dm_get_reserved_rq_based_ios() for use by DM targets and core code. Switch to sizing dm-mpath's mempool using DM core's configurable 'reserved_rq_based_ios'. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Frank Mayhar <fmayhar@google.com> Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Diffstat (limited to 'drivers/md/dm.c')
-rw-r--r--drivers/md/dm.c38
1 files changed, 37 insertions, 1 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index f2e5a50ee84..1e85f1da1ef 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -213,9 +213,41 @@ struct dm_md_mempools {
#define RESERVED_BIO_BASED_IOS 16
#define RESERVED_REQUEST_BASED_IOS 256
+#define RESERVED_MAX_IOS 1024
static struct kmem_cache *_io_cache;
static struct kmem_cache *_rq_tio_cache;
+/*
+ * Request-based DM's mempools' reserved IOs set by the user.
+ */
+static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
+
+static unsigned __dm_get_reserved_ios(unsigned *reserved_ios,
+ unsigned def, unsigned max)
+{
+ unsigned ios = ACCESS_ONCE(*reserved_ios);
+ unsigned modified_ios = 0;
+
+ if (!ios)
+ modified_ios = def;
+ else if (ios > max)
+ modified_ios = max;
+
+ if (modified_ios) {
+ (void)cmpxchg(reserved_ios, ios, modified_ios);
+ ios = modified_ios;
+ }
+
+ return ios;
+}
+
+unsigned dm_get_reserved_rq_based_ios(void)
+{
+ return __dm_get_reserved_ios(&reserved_rq_based_ios,
+ RESERVED_REQUEST_BASED_IOS, RESERVED_MAX_IOS);
+}
+EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);
+
static int __init local_init(void)
{
int r = -ENOMEM;
@@ -2878,7 +2910,7 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, u
front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
} else if (type == DM_TYPE_REQUEST_BASED) {
cachep = _rq_tio_cache;
- pool_size = RESERVED_REQUEST_BASED_IOS;
+ pool_size = dm_get_reserved_rq_based_ios();
front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
/* per_bio_data_size is not used. See __bind_mempools(). */
WARN_ON(per_bio_data_size != 0);
@@ -2936,6 +2968,10 @@ module_exit(dm_exit);
module_param(major, uint, 0);
MODULE_PARM_DESC(major, "The major number of the device mapper");
+
+module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
+
MODULE_DESCRIPTION(DM_NAME " driver");
MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");