在 2022/2/9 上午1:50, Mike Christie 写道:
On 1/25/22 2:38 AM, mingzhe.zou@xxxxxxxxxxxx wrote:
From: Mingzhe Zou <mingzhe.zou@xxxxxxxxxxxx>
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@xxxxxxxxxxxx>
---
drivers/target/iscsi/iscsi_target.c | 21 ++++++++++--
drivers/target/iscsi/iscsi_target.h | 17 ++++++++++
drivers/target/iscsi/iscsi_target_configfs.c | 34 ++++++++++++++++++++
drivers/target/iscsi/iscsi_target_login.c | 7 ++++
include/target/iscsi/iscsi_target_core.h | 1 +
5 files changed, 78 insertions(+), 2 deletions(-)
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 2c54c5d8412d..a18d3fc3cfd1 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -693,6 +693,11 @@ static int __init iscsi_target_init_module(void)
mutex_init(&auth_id_lock);
idr_init(&tiqn_idr);
+ /*
+ * allow all cpus run iscsi_ttx and iscsi_trx
I would just drop the comment. The "setall" in the function name
is pretty clear already.
I will remove it.
+ */
+ cpumask_setall(&__iscsi_allowed_cpumask);
+
ret = target_register_template(&iscsi_ops);
if (ret)
goto out;
@@ -3587,6 +3592,15 @@ static int iscsit_send_reject(
void iscsit_thread_get_cpumask(struct iscsi_conn *conn)
{
int ord, cpu;
+ cpumask_t conn_allowed_cpumask;
+
+ /*
+ * The available cpus set of iSCSI connection's RX/TX threads
+ */
Probably can drop the comment too since the variable names make it
known what we are doing.
I will remove it.
+ cpumask_and(&conn_allowed_cpumask,
+ &__iscsi_allowed_cpumask,
+ cpu_online_mask);
The formatting needs some fix ups. I think __iscsi_allowed_cpumask can fit on the
line above it and then cpu_online_mask should be moved over a couple spaces to
align with the opening "(".
I will reformat.
+
/*
* 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;
@@ -3821,6 +3836,7 @@ int iscsi_target_tx_thread(void *arg)
* Ensure that both TX and RX per connection kthreads
* are scheduled to run on the same CPU.
*/
+ iscsit_thread_reschedule(conn);
If we have multiple sessions to the same portal, could we end up racing
where session0's tx/rx threads call iscsit_thread_reschedule and
iscsit_thread_check_cpumask at the same time as session1's threads and
they end up taking the same cpus. They both could be running
iscsit_thread_get_cpumask at the same time, see he same masks values
and in the for_each_cpu loop think the same cpu is free.
Simply, this patch just adds a config item to skip some CPUs that are
bound to other threads,
not to change the calculation method of cpumask.
When the cpus_allowed_list in sysfs is modified, the tx/rx threads of
all sessions will clear current
cpumask and call iscsit_thread_reschedule and
iscsit_thread_check_cpumask to get a new value.
Because each session is allocated a unique bitmap_id in advance, then
calculate the cpumask
via bitmap_id. So the tx/rx threads of different sessions will be
scheduled to different CPUs (when
the number of CPUs is sufficient).
iscsit_thread_check_cpumask(conn, current, 1);
wait_event_interruptible(conn->queues_wq,
@@ -3966,6 +3982,7 @@ static void iscsit_get_rx_pdu(struct iscsi_conn *conn)
* Ensure that both TX and RX per connection kthreads
* are scheduled to run on the same CPU.
*/
+ iscsit_thread_reschedule(conn);
iscsit_thread_check_cpumask(conn, current, 0);
memset(&iov, 0, sizeof(struct kvec));
diff --git a/drivers/target/iscsi/iscsi_target.h b/drivers/target/iscsi/iscsi_target.h
index b35a96ded9c1..cb97a316d76d 100644
--- a/drivers/target/iscsi/iscsi_target.h
+++ b/drivers/target/iscsi/iscsi_target.h
@@ -57,4 +57,21 @@ extern struct kmem_cache *lio_r2t_cache;
extern struct ida sess_ida;
extern struct mutex auth_id_lock;
+extern cpumask_t __iscsi_allowed_cpumask;
I would rename to:
iscsit_allowed_cpumask
I will rename to iscsit_allowed_cpumas.
+
+static inline void iscsit_thread_reschedule(struct iscsi_conn *conn)
+{
+ /*
+ * If __iscsi_allowed_cpumask modified, reschedule iSCSI connection's
+ * RX/TX threads update conn->allowed_cpumask.
+ */
+ if (!cpumask_equal(&__iscsi_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,
+ &__iscsi_allowed_cpumask);
Fix up formatting like above.
I will reformat.
+ }
+}
+
#endif /*** ISCSI_TARGET_H ***/
diff --git a/drivers/target/iscsi/iscsi_target_configfs.c b/drivers/target/iscsi/iscsi_target_configfs.c
index 2a9de24a8bbe..dc12b1695838 100644
--- a/drivers/target/iscsi/iscsi_target_configfs.c
+++ b/drivers/target/iscsi/iscsi_target_configfs.c
@@ -1127,8 +1127,42 @@ static ssize_t lio_target_wwn_lio_version_show(struct config_item *item,
CONFIGFS_ATTR_RO(lio_target_wwn_, lio_version);
+cpumask_t __iscsi_allowed_cpumask;
Maybe better to put this in iscsi_target.c with the other vars like
it.
Originally I wanted to put it in struct iscsit_global and use it in
iscsit_thread_check_cpumask.
However iscsit_thread_check_cpumask is also called in cxgbit_target.c. I
don't know if I also
need to modify cxgbit at the same time, and I only modified two calls in
iscsi_target.c. I would
like to know how to handle in cxgbit_target.c?
I want to move 'static inline void iscsit_thread_check_cpumask' from
iscsi_target_core.h to
iscsi_target.c and EXPORT_SYMBOL(iscsit_thread_check_cpumask). Do you
agree it?
+
+static ssize_t lio_target_wwn_cpus_allowed_list_show(
+ struct config_item *item, char *page)
+{
+ return sprintf(page, "%*pbl\n",
+ cpumask_pr_args(&__iscsi_allowed_cpumask));
Formatting like above.
I will reformat.
+}
+
+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);
Are you supposed to do a before
using new_allowed_cpumask? It looks like other callers are doing it.
Other callers used cpumask_var_t, but the new_allowed_cpumask is cpumask_t.
I think just call cpumask_clear(&new_allowed_cpumask).
typedef struct cpumask { DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t;
typedef struct cpumask cpumask_var_t[1];
+
+ kfree(orig);
+ if (ret != 0)
+ return ret;
+
+ cpumask_copy(&__iscsi_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..910f35e4648a 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;
+ }
I think in iscsit_free_conn you need a:
free_cpumask_var(conn->allowed_cpumask);
to go with this allocation.
This is bug. I will fix up in v2.
+
return conn;
+free_conn_cpumask:
+ free_cpumask_var(conn->allowed_cpumask);
I think you wanted conn->conn_cpumask here.
This is bug. I will fix up in v2.
free_conn_ops:
kfree(conn->conn_ops);
put_transport:
diff --git a/include/target/iscsi/iscsi_target_core.h b/include/target/iscsi/iscsi_target_core.h
index 1eccb2ac7d02..c5e9cad187cf 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 */
