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| author | Michal Schmidt <mschmidt@redhat.com> | 2023-04-12 10:19:27 +0200 |
|---|---|---|
| committer | Tony Nguyen <anthony.l.nguyen@intel.com> | 2023-04-20 16:33:14 -0700 |
| commit | f86d6f9c49f67b05d117495dc440aaa18c66a9da (patch) | |
| tree | 545fb6047a44ad0b28140df997453aff9742bfd8 /drivers/net/ethernet/intel/ice/ice_controlq.c | |
| parent | 84817ab66fd0d9cde371fcb020f610ba808585bb (diff) | |
| download | linux-f86d6f9c49f67b05d117495dc440aaa18c66a9da.tar.gz linux-f86d6f9c49f67b05d117495dc440aaa18c66a9da.tar.bz2 linux-f86d6f9c49f67b05d117495dc440aaa18c66a9da.zip | |
ice: sleep, don't busy-wait, for ICE_CTL_Q_SQ_CMD_TIMEOUT
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 the timeout in jiffies.
ICE_CTL_Q_SQ_CMD_TIMEOUT is used 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 received a report of high CPU usage with ptp4l where the busy-waiting
in ice_sq_send_cmd dominated the profile. This patch has been tested in
that usecase too and it made a huge improvement there.
Tested-by: Brent Rowsell <browsell@redhat.com>
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Reviewed-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Tested-by: Sunitha Mekala <sunithax.d.mekala@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Diffstat (limited to 'drivers/net/ethernet/intel/ice/ice_controlq.c')
| -rw-r--r-- | drivers/net/ethernet/intel/ice/ice_controlq.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/net/ethernet/intel/ice/ice_controlq.c b/drivers/net/ethernet/intel/ice/ice_controlq.c index c8fb10106ec3..d2faf1baad2f 100644 --- a/drivers/net/ethernet/intel/ice/ice_controlq.c +++ b/drivers/net/ethernet/intel/ice/ice_controlq.c @@ -964,7 +964,7 @@ 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; @@ -1057,13 +1057,14 @@ 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 + ICE_CTL_Q_SQ_CMD_TIMEOUT; do { if (ice_sq_done(hw, cq)) break; - udelay(ICE_CTL_Q_SQ_CMD_USEC); - total_delay++; - } while (total_delay < ICE_CTL_Q_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)) { |