[Intel-wired-lan] [PATCH net-next 2/4] ice: sleep, don't busy-wait, for sq_cmd_timeout
Michal Schmidt
mschmidt at redhat.com
Sat Apr 1 17:26:57 UTC 2023
The driver polls for ice_sq_done() with a 100 µs period for up to 1 s
and it uses udelay to do that.
Let's use usleep_range instead. We know sleeping is allowed here,
because we're holding a mutex (cq->sq_lock). To preserve the total
max waiting time, measure cq->sq_cmd_timeout in jiffies.
The sq_cmd_timeout is referenced also in ice_release_res(), but there
the polling period is 1 ms (i.e. 10 times longer). Since the timeout
was expressed in terms of the number of loops, the total timeout in this
function is 10 s. I do not know if this is intentional. This patch keeps
it.
The patch lowers the CPU usage of the ice-gnss-<dev_name> kernel thread
on my system from ~8 % to less than 1 %.
I saw a report of high CPU usage with ptp4l where the busy-waiting in
ice_sq_send_cmd dominated the profile. The patch should help with that.
Signed-off-by: Michal Schmidt <mschmidt at redhat.com>
---
drivers/net/ethernet/intel/ice/ice_common.c | 14 +++++++-------
drivers/net/ethernet/intel/ice/ice_controlq.c | 9 +++++----
drivers/net/ethernet/intel/ice/ice_controlq.h | 2 +-
3 files changed, 13 insertions(+), 12 deletions(-)
diff --git a/drivers/net/ethernet/intel/ice/ice_common.c b/drivers/net/ethernet/intel/ice/ice_common.c
index c2fda4fa4188..14cffe49fa8c 100644
--- a/drivers/net/ethernet/intel/ice/ice_common.c
+++ b/drivers/net/ethernet/intel/ice/ice_common.c
@@ -1992,19 +1992,19 @@ ice_acquire_res(struct ice_hw *hw, enum ice_aq_res_ids res,
*/
void ice_release_res(struct ice_hw *hw, enum ice_aq_res_ids res)
{
- u32 total_delay = 0;
+ unsigned long timeout;
int status;
- status = ice_aq_release_res(hw, res, 0, NULL);
-
/* there are some rare cases when trying to release the resource
* results in an admin queue timeout, so handle them correctly
*/
- while ((status == -EIO) && (total_delay < hw->adminq.sq_cmd_timeout)) {
- mdelay(1);
+ timeout = jiffies + 10 * hw->adminq.sq_cmd_timeout;
+ do {
status = ice_aq_release_res(hw, res, 0, NULL);
- total_delay++;
- }
+ if (status != -EIO)
+ break;
+ usleep_range(1000, 2000);
+ } while (time_before(jiffies, timeout));
}
/**
diff --git a/drivers/net/ethernet/intel/ice/ice_controlq.c b/drivers/net/ethernet/intel/ice/ice_controlq.c
index 6bcfee295991..10125e8aa555 100644
--- a/drivers/net/ethernet/intel/ice/ice_controlq.c
+++ b/drivers/net/ethernet/intel/ice/ice_controlq.c
@@ -967,7 +967,7 @@ ice_sq_send_cmd(struct ice_hw *hw, struct ice_ctl_q_info *cq,
struct ice_aq_desc *desc_on_ring;
bool cmd_completed = false;
struct ice_sq_cd *details;
- u32 total_delay = 0;
+ unsigned long timeout;
int status = 0;
u16 retval = 0;
u32 val = 0;
@@ -1060,13 +1060,14 @@ ice_sq_send_cmd(struct ice_hw *hw, struct ice_ctl_q_info *cq,
cq->sq.next_to_use = 0;
wr32(hw, cq->sq.tail, cq->sq.next_to_use);
+ timeout = jiffies + cq->sq_cmd_timeout;
do {
if (ice_sq_done(hw, cq))
break;
- udelay(ICE_CTL_Q_SQ_CMD_USEC);
- total_delay++;
- } while (total_delay < cq->sq_cmd_timeout);
+ usleep_range(ICE_CTL_Q_SQ_CMD_USEC,
+ ICE_CTL_Q_SQ_CMD_USEC * 3 / 2);
+ } while (time_before(jiffies, timeout));
/* if ready, copy the desc back to temp */
if (ice_sq_done(hw, cq)) {
diff --git a/drivers/net/ethernet/intel/ice/ice_controlq.h b/drivers/net/ethernet/intel/ice/ice_controlq.h
index c07e9cc9fc6e..f2d3b115ae0b 100644
--- a/drivers/net/ethernet/intel/ice/ice_controlq.h
+++ b/drivers/net/ethernet/intel/ice/ice_controlq.h
@@ -34,7 +34,7 @@ enum ice_ctl_q {
};
/* Control Queue timeout settings - max delay 1s */
-#define ICE_CTL_Q_SQ_CMD_TIMEOUT 10000 /* Count 10000 times */
+#define ICE_CTL_Q_SQ_CMD_TIMEOUT HZ /* Wait max 1s */
#define ICE_CTL_Q_SQ_CMD_USEC 100 /* Check every 100usec */
#define ICE_CTL_Q_ADMIN_INIT_TIMEOUT 10 /* Count 10 times */
#define ICE_CTL_Q_ADMIN_INIT_MSEC 100 /* Check every 100msec */
--
2.39.2
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