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f86d6f9c49
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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.