block/rnbd-clt: Support polling mode for IO latency optimization
RNBD can make double-queues for irq-mode and poll-mode.
For example, on 4-CPU system 8 request-queues are created,
4 for irq-mode and 4 for poll-mode.
If the IO has HIPRI flag, the block-layer will call .poll function
of RNBD. Then IO is sent to the poll-mode queue.
Add optional nr_poll_queues argument for map_devices interface.
To support polling of RNBD, RTRS client creates connections
for both of irq-mode and direct-poll-mode.
For example, on 4-CPU system it could've create 5 connections:
con[0] => user message (softirq cq)
con[1:4] => softirq cq
After this patch, it can create 9 connections:
con[0] => user message (softirq cq)
con[1:4] => softirq cq
con[5:8] => DIRECT-POLL cq
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Acked-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/20210419073722.15351-14-gi-oh.kim@ionos.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/block/rnbd/rnbd-clt-sysfs.c b/drivers/block/rnbd/rnbd-clt-sysfs.c
index 49015f4..2b6305e 100644
--- a/drivers/block/rnbd/rnbd-clt-sysfs.c
+++ b/drivers/block/rnbd/rnbd-clt-sysfs.c
@@ -34,6 +34,7 @@ enum {
RNBD_OPT_DEV_PATH = 1 << 2,
RNBD_OPT_ACCESS_MODE = 1 << 3,
RNBD_OPT_SESSNAME = 1 << 6,
+ RNBD_OPT_NR_POLL_QUEUES = 1 << 7,
};
static const unsigned int rnbd_opt_mandatory[] = {
@@ -42,12 +43,13 @@ static const unsigned int rnbd_opt_mandatory[] = {
};
static const match_table_t rnbd_opt_tokens = {
- {RNBD_OPT_PATH, "path=%s" },
- {RNBD_OPT_DEV_PATH, "device_path=%s"},
- {RNBD_OPT_DEST_PORT, "dest_port=%d" },
- {RNBD_OPT_ACCESS_MODE, "access_mode=%s"},
- {RNBD_OPT_SESSNAME, "sessname=%s" },
- {RNBD_OPT_ERR, NULL },
+ {RNBD_OPT_PATH, "path=%s" },
+ {RNBD_OPT_DEV_PATH, "device_path=%s" },
+ {RNBD_OPT_DEST_PORT, "dest_port=%d" },
+ {RNBD_OPT_ACCESS_MODE, "access_mode=%s" },
+ {RNBD_OPT_SESSNAME, "sessname=%s" },
+ {RNBD_OPT_NR_POLL_QUEUES, "nr_poll_queues=%d" },
+ {RNBD_OPT_ERR, NULL },
};
struct rnbd_map_options {
@@ -57,6 +59,7 @@ struct rnbd_map_options {
char *pathname;
u16 *dest_port;
enum rnbd_access_mode *access_mode;
+ u32 *nr_poll_queues;
};
static int rnbd_clt_parse_map_options(const char *buf, size_t max_path_cnt,
@@ -68,7 +71,7 @@ static int rnbd_clt_parse_map_options(const char *buf, size_t max_path_cnt,
int opt_mask = 0;
int token;
int ret = -EINVAL;
- int i, dest_port;
+ int i, dest_port, nr_poll_queues;
int p_cnt = 0;
options = kstrdup(buf, GFP_KERNEL);
@@ -178,6 +181,19 @@ static int rnbd_clt_parse_map_options(const char *buf, size_t max_path_cnt,
kfree(p);
break;
+ case RNBD_OPT_NR_POLL_QUEUES:
+ if (match_int(args, &nr_poll_queues) || nr_poll_queues < -1 ||
+ nr_poll_queues > (int)nr_cpu_ids) {
+ pr_err("bad nr_poll_queues parameter '%d'\n",
+ nr_poll_queues);
+ ret = -EINVAL;
+ goto out;
+ }
+ if (nr_poll_queues == -1)
+ nr_poll_queues = nr_cpu_ids;
+ *opt->nr_poll_queues = nr_poll_queues;
+ break;
+
default:
pr_err("map_device: Unknown parameter or missing value '%s'\n",
p);
@@ -227,6 +243,19 @@ static ssize_t state_show(struct kobject *kobj,
static struct kobj_attribute rnbd_clt_state_attr = __ATTR_RO(state);
+static ssize_t nr_poll_queues_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *page)
+{
+ struct rnbd_clt_dev *dev;
+
+ dev = container_of(kobj, struct rnbd_clt_dev, kobj);
+
+ return sysfs_emit(page, "%d\n", dev->nr_poll_queues);
+}
+
+static struct kobj_attribute rnbd_clt_nr_poll_queues =
+ __ATTR_RO(nr_poll_queues);
+
static ssize_t mapping_path_show(struct kobject *kobj,
struct kobj_attribute *attr, char *page)
{
@@ -421,6 +450,7 @@ static struct attribute *rnbd_dev_attrs[] = {
&rnbd_clt_state_attr.attr,
&rnbd_clt_session_attr.attr,
&rnbd_clt_access_mode.attr,
+ &rnbd_clt_nr_poll_queues.attr,
NULL,
};
@@ -469,7 +499,7 @@ static ssize_t rnbd_clt_map_device_show(struct kobject *kobj,
char *page)
{
return scnprintf(page, PAGE_SIZE,
- "Usage: echo \"[dest_port=server port number] sessname=<name of the rtrs session> path=<[srcaddr@]dstaddr> [path=<[srcaddr@]dstaddr>] device_path=<full path on remote side> [access_mode=<ro|rw|migration>]\" > %s\n\naddr ::= [ ip:<ipv4> | ip:<ipv6> | gid:<gid> ]\n",
+ "Usage: echo \"[dest_port=server port number] sessname=<name of the rtrs session> path=<[srcaddr@]dstaddr> [path=<[srcaddr@]dstaddr>] device_path=<full path on remote side> [access_mode=<ro|rw|migration>] [nr_poll_queues=<number of queues>]\" > %s\n\naddr ::= [ ip:<ipv4> | ip:<ipv6> | gid:<gid> ]\n",
attr->attr.name);
}
@@ -541,6 +571,7 @@ static ssize_t rnbd_clt_map_device_store(struct kobject *kobj,
char sessname[NAME_MAX];
enum rnbd_access_mode access_mode = RNBD_ACCESS_RW;
u16 port_nr = RTRS_PORT;
+ u32 nr_poll_queues = 0;
struct sockaddr_storage *addrs;
struct rtrs_addr paths[6];
@@ -552,6 +583,7 @@ static ssize_t rnbd_clt_map_device_store(struct kobject *kobj,
opt.pathname = pathname;
opt.dest_port = &port_nr;
opt.access_mode = &access_mode;
+ opt.nr_poll_queues = &nr_poll_queues;
addrs = kcalloc(ARRAY_SIZE(paths) * 2, sizeof(*addrs), GFP_KERNEL);
if (!addrs)
return -ENOMEM;
@@ -565,12 +597,13 @@ static ssize_t rnbd_clt_map_device_store(struct kobject *kobj,
if (ret)
goto out;
- pr_info("Mapping device %s on session %s, (access_mode: %s)\n",
+ pr_info("Mapping device %s on session %s, (access_mode: %s, nr_poll_queues: %d)\n",
pathname, sessname,
- rnbd_access_mode_str(access_mode));
+ rnbd_access_mode_str(access_mode),
+ nr_poll_queues);
dev = rnbd_clt_map_device(sessname, paths, path_cnt, port_nr, pathname,
- access_mode);
+ access_mode, nr_poll_queues);
if (IS_ERR(dev)) {
ret = PTR_ERR(dev);
goto out;