[PATCH v3] target: add iscsi/cpus_allowed_list in configfs

mingzhe.zou
2022-03-01T07:55:10Z

From: Mingzhe Zou <mingzhe.zou@easystack.cn>

The RX/TX threads for iSCSI connection can be scheduled to
any online cpus, and will not be rescheduled.

If bind other heavy load threads with iSCSI connection
RX/TX thread to the same cpu, the iSCSI performance will
be worse.

This patch add iscsi/cpus_allowed_list in configfs. The
available cpus set of iSCSI connection RX/TX threads is
allowed_cpus & online_cpus. If it is modified, all RX/TX
threads will be rescheduled.

Signed-off-by: Mingzhe Zou <mingzhe.zou@easystack.cn>
---
drivers/target/iscsi/iscsi_target.c | 77 +++++++++++++++++++-
drivers/target/iscsi/iscsi_target_configfs.c | 32 ++++++++
drivers/target/iscsi/iscsi_target_login.c | 8 ++
include/target/iscsi/iscsi_target_core.h | 31 ++------
4 files changed, 120 insertions(+), 28 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 2c54c5d8412d..6fe6a6bab3f4 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -702,13 +702,19 @@ static int __init iscsi_target_init_module(void)
if (!iscsit_global->ts_bitmap)
goto configfs_out;

+ if (!zalloc_cpumask_var(&iscsit_global->allowed_cpumask, GFP_KERNEL)) {
+ pr_err("Unable to allocate iscsit_global->allowed_cpumask\n");
+ goto bitmap_out;
+ }
+ cpumask_setall(iscsit_global->allowed_cpumask);
+
lio_qr_cache = kmem_cache_create("lio_qr_cache",
sizeof(struct iscsi_queue_req),
__alignof__(struct iscsi_queue_req), 0, NULL);
if (!lio_qr_cache) {
pr_err("Unable to kmem_cache_create() for"
" lio_qr_cache\n");
- goto bitmap_out;
+ goto cpumask_out;
}

lio_dr_cache = kmem_cache_create("lio_dr_cache",
@@ -753,6 +759,8 @@ static int __init iscsi_target_init_module(void)
kmem_cache_destroy(lio_dr_cache);
qr_out:
kmem_cache_destroy(lio_qr_cache);
+cpumask_out:
+ free_cpumask_var(iscsit_global->allowed_cpumask);
bitmap_out:
vfree(iscsit_global->ts_bitmap);
configfs_out:
@@ -782,6 +790,7 @@ static void __exit iscsi_target_cleanup_module(void)

target_unregister_template(&iscsi_ops);

+ free_cpumask_var(iscsit_global->allowed_cpumask);
vfree(iscsit_global->ts_bitmap);
kfree(iscsit_global);
}
@@ -3587,6 +3596,11 @@ static int iscsit_send_reject(
void iscsit_thread_get_cpumask(struct iscsi_conn *conn)
{
int ord, cpu;
+ cpumask_t conn_allowed_cpumask;
+
+ cpumask_and(&conn_allowed_cpumask, iscsit_global->allowed_cpumask,
+ cpu_online_mask);
+
/*
* bitmap_id is assigned from iscsit_global->ts_bitmap from
* within iscsit_start_kthreads()
@@ -3595,8 +3609,9 @@ void iscsit_thread_get_cpumask(struct iscsi_conn *conn)
* iSCSI connection's RX/TX threads will be scheduled to
* execute upon.
*/
- ord = conn->bitmap_id % cpumask_weight(cpu_online_mask);
- for_each_online_cpu(cpu) {
+ cpumask_clear(conn->conn_cpumask);
+ ord = conn->bitmap_id % cpumask_weight(&conn_allowed_cpumask);
+ for_each_cpu(cpu, &conn_allowed_cpumask) {
if (ord-- == 0) {
cpumask_set_cpu(cpu, conn->conn_cpumask);
return;
@@ -3609,6 +3624,62 @@ void iscsit_thread_get_cpumask(struct iscsi_conn *conn)
cpumask_setall(conn->conn_cpumask);
}

+static void iscsit_thread_reschedule(struct iscsi_conn *conn)
+{
+ /*
+ * If iscsit_global->allowed_cpumask modified, reschedule iSCSI
+ * connection's RX/TX threads update conn->allowed_cpumask.
+ */
+ if (!cpumask_equal(iscsit_global->allowed_cpumask,
+ conn->allowed_cpumask)) {
+ iscsit_thread_get_cpumask(conn);
+ conn->conn_tx_reset_cpumask = 1;
+ conn->conn_rx_reset_cpumask = 1;
+ cpumask_copy(conn->allowed_cpumask,
+ iscsit_global->allowed_cpumask);
+ }
+}
+
+void iscsit_thread_check_cpumask(
+ struct iscsi_conn *conn,
+ struct task_struct *p,
+ int mode)
+{
+ /*
+ * The TX and RX threads maybe call iscsit_thread_check_cpumask()
+ * at the same time. The RX thread might be faster and return from
+ * iscsit_thread_reschedule() with conn_rx_reset_cpumask set to 0.
+ * Then the TX thread sets it back to 1.
+ * The next time the RX thread loops, it sees conn_rx_reset_cpumask
+ * set to 1 and calls set_cpus_allowed_ptr() again and set it to 0.
+ */
+ iscsit_thread_reschedule(conn);
+
+ /*
+ * mode == 1 signals iscsi_target_tx_thread() usage.
+ * mode == 0 signals iscsi_target_rx_thread() usage.
+ */
+ if (mode == 1) {
+ if (!conn->conn_tx_reset_cpumask)
+ return;
+ } else {
+ if (!conn->conn_rx_reset_cpumask)
+ return;
+ }
+
+ /*
+ * Update the CPU mask for this single kthread so that
+ * both TX and RX kthreads are scheduled to run on the
+ * same CPU.
+ */
+ set_cpus_allowed_ptr(p, conn->conn_cpumask);
+ if (mode == 1)
+ conn->conn_tx_reset_cpumask = 0;
+ else
+ conn->conn_rx_reset_cpumask = 0;
+}
+EXPORT_SYMBOL(iscsit_thread_check_cpumask);
+
int
iscsit_immediate_queue(struct iscsi_conn *conn, struct iscsi_cmd *cmd, int state)
{
diff --git a/drivers/target/iscsi/iscsi_target_configfs.c b/drivers/target/iscsi/iscsi_target_configfs.c
index 2a9de24a8bbe..0cedcfe207b5 100644
--- a/drivers/target/iscsi/iscsi_target_configfs.c
+++ b/drivers/target/iscsi/iscsi_target_configfs.c
@@ -1127,8 +1127,40 @@ static ssize_t lio_target_wwn_lio_version_show(struct config_item *item,

CONFIGFS_ATTR_RO(lio_target_wwn_, lio_version);

+static ssize_t lio_target_wwn_cpus_allowed_list_show(
+ struct config_item *item, char *page)
+{
+ return sprintf(page, "%*pbl\n",
+ cpumask_pr_args(iscsit_global->allowed_cpumask));
+}
+
+static ssize_t lio_target_wwn_cpus_allowed_list_store(
+ struct config_item *item, const char *page, size_t count)
+{
+ int ret;
+ char *orig;
+ cpumask_t new_allowed_cpumask;
+
+ orig = kstrdup(page, GFP_KERNEL);
+ if (!orig)
+ return -ENOMEM;
+
+ cpumask_clear(&new_allowed_cpumask);
+ ret = cpulist_parse(orig, &new_allowed_cpumask);
+
+ kfree(orig);
+ if (ret != 0)
+ return ret;
+
+ cpumask_copy(iscsit_global->allowed_cpumask, &new_allowed_cpumask);
+ return count;
+}
+
+CONFIGFS_ATTR(lio_target_wwn_, cpus_allowed_list);
+
static struct configfs_attribute *lio_target_wwn_attrs[] = {
&lio_target_wwn_attr_lio_version,
+ &lio_target_wwn_attr_cpus_allowed_list,
NULL,
};

diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index 1a9c50401bdb..9c01fb864585 100644
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -1129,8 +1129,15 @@ static struct iscsi_conn *iscsit_alloc_conn(struct iscsi_np *np)
goto free_conn_ops;
}

+ if (!zalloc_cpumask_var(&conn->allowed_cpumask, GFP_KERNEL)) {
+ pr_err("Unable to allocate conn->allowed_cpumask\n");
+ goto free_conn_cpumask;
+ }
+
return conn;

+free_conn_cpumask:
+ free_cpumask_var(conn->conn_cpumask);
free_conn_ops:
kfree(conn->conn_ops);
put_transport:
@@ -1142,6 +1149,7 @@ static struct iscsi_conn *iscsit_alloc_conn(struct iscsi_np *np)

void iscsit_free_conn(struct iscsi_conn *conn)
{
+ free_cpumask_var(conn->allowed_cpumask);
free_cpumask_var(conn->conn_cpumask);
kfree(conn->conn_ops);
iscsit_put_transport(conn->conn_transport);
diff --git a/include/target/iscsi/iscsi_target_core.h b/include/target/iscsi/iscsi_target_core.h
index 1eccb2ac7d02..adc87de0362b 100644
--- a/include/target/iscsi/iscsi_target_core.h
+++ b/include/target/iscsi/iscsi_target_core.h
@@ -580,6 +580,7 @@ struct iscsi_conn {
struct ahash_request *conn_tx_hash;
/* Used for scheduling TX and RX connection kthreads */
cpumask_var_t conn_cpumask;
+ cpumask_var_t allowed_cpumask;
unsigned int conn_rx_reset_cpumask:1;
unsigned int conn_tx_reset_cpumask:1;
/* list_head of struct iscsi_cmd for this connection */
@@ -878,6 +879,7 @@ struct iscsit_global {
/* Thread Set bitmap pointer */
unsigned long *ts_bitmap;
spinlock_t ts_bitmap_lock;
+ cpumask_var_t allowed_cpumask;
/* Used for iSCSI discovery session authentication */
struct iscsi_node_acl discovery_acl;
struct iscsi_portal_group *discovery_tpg;
@@ -898,29 +900,8 @@ static inline u32 session_get_next_ttt(struct iscsi_session *session)

extern struct iscsi_cmd *iscsit_find_cmd_from_itt(struct iscsi_conn *, itt_t);

-static inline void iscsit_thread_check_cpumask(
- struct iscsi_conn *conn,
- struct task_struct *p,
- int mode)
-{
- /*
- * mode == 1 signals iscsi_target_tx_thread() usage.
- * mode == 0 signals iscsi_target_rx_thread() usage.
- */
- if (mode == 1) {
- if (!conn->conn_tx_reset_cpumask)
- return;
- conn->conn_tx_reset_cpumask = 0;
- } else {
- if (!conn->conn_rx_reset_cpumask)
- return;
- conn->conn_rx_reset_cpumask = 0;
- }
- /*
- * Update the CPU mask for this single kthread so that
- * both TX and RX kthreads are scheduled to run on the
- * same CPU.
- */
- set_cpus_allowed_ptr(p, conn->conn_cpumask);
-}
+extern void iscsit_thread_check_cpumask(struct iscsi_conn *conn,
+ struct task_struct *p,
+ int mode);
+
#endif /* ISCSI_TARGET_CORE_H */
--
2.17.1