On 2/2/21 9:06 AM, [email protected] wrote:
> From: "Paul E. McKenney" <[email protected]>
>
> Code that checks for clock desynchronization must itself be tested, so
> this commit creates a new clocksource.inject_delay_shift_percpu= kernel
> boot parameter that adds or subtracts a large value from the check read,
> using the specified bit of the CPU ID to determine whether to add or
> to subtract.
>
> Cc: John Stultz <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Stephen Boyd <[email protected]>
> Cc: Jonathan Corbet <[email protected]>
> Cc: Mark Rutland <[email protected]>
> Cc: Marc Zyngier <[email protected]>
> Cc: Andi Kleen <[email protected]>
> Reported-by: Chris Mason <[email protected]>
> Signed-off-by: Paul E. McKenney <[email protected]>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++
> kernel/time/clocksource.c | 10 +++++++++-
> 2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt
> b/Documentation/admin-guide/kernel-parameters.txt
> index 9965266..f561e94 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -593,6 +593,15 @@
> times the value specified for inject_delay_freq
> of consecutive non-delays.
>
> + clocksource.inject_delay_shift_percpu= [KNL]
> + Shift count to obtain bit from CPU number to
> + determine whether to shift the time of the per-CPU
> + clock under test ahead or behind. For example,
It's a good think that you give an example -- it helps a little bit.
That sentence above needs to be rewritten...
> + setting this to the value four will result in
> + alternating groups of 16 CPUs shifting ahead and
> + the rest of the CPUs shifting behind. The default
> + value of -1 disable this type of error injection.
disables
> +
> clocksource.max_read_retries= [KNL]
> Number of clocksource_watchdog() retries due to
> external delays before the clock will be marked
--
~Randy
