Re: [PATCH RFC net-next] igb: adjust SYSTIM register using TIMADJ register

2018-04-20 Thread Richard Cochran
On Fri, Apr 20, 2018 at 02:56:36PM -0500, Kshitiz Gupta wrote: > Currently the driver adjusts time by reading the current time and then > modifying it before writing to SYSTIM register. This can introduce > inaccuracies in SYSTIM. With a PREEMPT_RT kernel, spinlocks may be > interrupted, which in

[PATCH RFC net-next] igb: adjust SYSTIM register using TIMADJ register

2018-04-20 Thread Kshitiz Gupta
Currently the driver adjusts time by reading the current time and then modifying it before writing to SYSTIM register. This can introduce inaccuracies in SYSTIM. With a PREEMPT_RT kernel, spinlocks may be interrupted, which in the existing implementation may lead to increased time between the read