From: Gioh Kim <gi-oh.kim@xxxxxxxxxxxxxxx>
This patch adds new multipath policy: min-latency.
Client checks the latency of each path when it sends the heart-beat.
And it sends IO to the path with the minimum latency.
Signed-off-by: Gioh Kim <gi-oh.kim@xxxxxxxxx>
Signed-off-by: Jack Wang <jinpu.wang@xxxxxxxxx>
---
drivers/infiniband/ulp/rtrs/rtrs-clt-sysfs.c | 18 +++++--
drivers/infiniband/ulp/rtrs/rtrs-clt.c | 57 +++++++++++++++++++-
drivers/infiniband/ulp/rtrs/rtrs-clt.h | 1 +
drivers/infiniband/ulp/rtrs/rtrs-pri.h | 2 +
drivers/infiniband/ulp/rtrs/rtrs.c | 3 ++
5 files changed, 77 insertions(+), 4 deletions(-)
diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt-sysfs.c b/drivers/infiniband/ulp/rtrs/rtrs-clt-sysfs.c
index c502dcbae9bb..bc46b7a99ba0 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs-clt-sysfs.c
+++ b/drivers/infiniband/ulp/rtrs/rtrs-clt-sysfs.c
@@ -101,6 +101,8 @@ static ssize_t mpath_policy_show(struct device *dev,
case MP_POLICY_MIN_INFLIGHT:
return sysfs_emit(page, "min-inflight (MI: %d)\n",
clt->mp_policy);
+ case MP_POLICY_MIN_LATENCY:
+ return sprintf(page, "min-latency (ML: %d)\n", clt->mp_policy);
default:
return sysfs_emit(page, "Unknown (%d)\n", clt->mp_policy);
}
@@ -114,22 +116,32 @@ static ssize_t mpath_policy_store(struct device *dev,
struct rtrs_clt *clt;
int value;
int ret;
+ size_t len = 0;
clt = container_of(dev, struct rtrs_clt, dev);
ret = kstrtoint(buf, 10, &value);
if (!ret && (value == MP_POLICY_RR ||
- value == MP_POLICY_MIN_INFLIGHT)) {
+ value == MP_POLICY_MIN_INFLIGHT ||
+ value == MP_POLICY_MIN_LATENCY)) {
clt->mp_policy = value;
return count;
}
+ /* distinguish "mi" and "min-latency" with length */
+ len = strnlen(buf, NAME_MAX);
+ if (buf[len - 1] == '\n')
+ len--;
+
if (!strncasecmp(buf, "round-robin", 11) ||
- !strncasecmp(buf, "rr", 2))
+ (len == 2 && !strncasecmp(buf, "rr", 2)))
clt->mp_policy = MP_POLICY_RR;
else if (!strncasecmp(buf, "min-inflight", 12) ||
- !strncasecmp(buf, "mi", 2))
+ (len == 2 && !strncasecmp(buf, "mi", 2)))
clt->mp_policy = MP_POLICY_MIN_INFLIGHT;
+ else if (!strncasecmp(buf, "min-latency", 11) ||
+ (len == 2 && !strncasecmp(buf, "ml", 2)))
+ clt->mp_policy = MP_POLICY_MIN_LATENCY;
else
return -EINVAL;
diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
index 7e72f0911cf2..3e7b78d71362 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs-clt.c
+++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
@@ -636,6 +636,8 @@ static void rtrs_clt_rdma_done(struct ib_cq *cq, struct ib_wc *wc)
} else if (imm_type == RTRS_HB_ACK_IMM) {
WARN_ON(con->c.cid);
sess->s.hb_missed_cnt = 0;
+ sess->s.hb_cur_latency =
+ ktime_sub(ktime_get(), sess->s.hb_last_sent);
if (sess->flags & RTRS_MSG_NEW_RKEY_F)
return rtrs_clt_recv_done(con, wc);
} else {
@@ -837,6 +839,57 @@ static struct rtrs_clt_sess *get_next_path_min_inflight(struct path_it *it)
return min_path;
}
+/**
+ * get_next_path_min_latency() - Returns path with minimal latency.
+ * @it: the path pointer
+ *
+ * Return: a path with the lowest latency or NULL if all paths are tried
+ *
+ * Locks:
+ * rcu_read_lock() must be hold.
+ *
+ * Related to @MP_POLICY_MIN_LATENCY
+ *
+ * This DOES skip an already-tried path.
+ * There is a skip-list to skip a path if the path has tried but failed.
+ * It will try the minimum latency path and then the second minimum latency
+ * path and so on. Finally it will return NULL if all paths are tried.
+ * Therefore the caller MUST check the returned
+ * path is NULL and trigger the IO error.
+ */
+static struct rtrs_clt_sess *get_next_path_min_latency(struct path_it *it)
+{
+ struct rtrs_clt_sess *min_path = NULL;
+ struct rtrs_clt *clt = it->clt;
+ struct rtrs_clt_sess *sess;
+ ktime_t min_latency = INT_MAX;
+ ktime_t latency;
+
+ list_for_each_entry_rcu(sess, &clt->paths_list, s.entry) {
+ if (unlikely(READ_ONCE(sess->state) != RTRS_CLT_CONNECTED))
+ continue;
+
+ if (unlikely(!list_empty(raw_cpu_ptr(sess->mp_skip_entry))))
+ continue;
+
+ latency = sess->s.hb_cur_latency;
+
+ if (latency < min_latency) {
+ min_latency = latency;
+ min_path = sess;
+ }
+ }
+
+ /*
+ * add the path to the skip list, so that next time we can get
+ * a different one
+ */
+ if (min_path)
+ list_add(raw_cpu_ptr(min_path->mp_skip_entry), &it->skip_list);
+
+ return min_path;
+}
+
static inline void path_it_init(struct path_it *it, struct rtrs_clt *clt)
{
INIT_LIST_HEAD(&it->skip_list);
@@ -845,8 +898,10 @@ static inline void path_it_init(struct path_it *it, struct rtrs_clt *clt)
if (clt->mp_policy == MP_POLICY_RR)
it->next_path = get_next_path_rr;
- else
+ else if (clt->mp_policy == MP_POLICY_MIN_INFLIGHT)
it->next_path = get_next_path_min_inflight;
+ else
+ it->next_path = get_next_path_min_latency;
}
static inline void path_it_deinit(struct path_it *it)
diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.h b/drivers/infiniband/ulp/rtrs/rtrs-clt.h
index 59ea2ec44fe5..5c0cea8dd83e 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs-clt.h
+++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.h
@@ -30,6 +30,7 @@ enum rtrs_clt_state {
enum rtrs_mp_policy {
MP_POLICY_RR,
MP_POLICY_MIN_INFLIGHT,
+ MP_POLICY_MIN_LATENCY,
};
/* see Documentation/ABI/testing/sysfs-class-rtrs-client for details */
diff --git a/drivers/infiniband/ulp/rtrs/rtrs-pri.h b/drivers/infiniband/ulp/rtrs/rtrs-pri.h
index 1b31bda9ca78..bcad5e2168c5 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs-pri.h
+++ b/drivers/infiniband/ulp/rtrs/rtrs-pri.h
@@ -112,6 +112,8 @@ struct rtrs_sess {
unsigned int hb_interval_ms;
unsigned int hb_missed_cnt;
unsigned int hb_missed_max;
+ ktime_t hb_last_sent;
+ ktime_t hb_cur_latency;
};
/* rtrs information unit */
diff --git a/drivers/infiniband/ulp/rtrs/rtrs.c b/drivers/infiniband/ulp/rtrs/rtrs.c
index bc08b7f6e5e2..a7847282a2eb 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs.c
+++ b/drivers/infiniband/ulp/rtrs/rtrs.c
@@ -337,6 +337,9 @@ static void hb_work(struct work_struct *work)
schedule_hb(sess);
return;
}
+
+ sess->hb_last_sent = ktime_get();
+
imm = rtrs_to_imm(RTRS_HB_MSG_IMM, 0);
err = rtrs_post_rdma_write_imm_empty(usr_con, sess->hb_cqe, imm,
0, NULL);
--
2.25.1
