On Wednesday, November 6, 2019 12:55:01 PM CET Zhenzhong Duan wrote:
> As user can adjust guest_halt_poll_grow_start and guest_halt_poll_ns
> which leads to cpu_halt_poll_us beyond the two boundaries. This patch
> ensures cpu_halt_poll_us in that scope.
>
> If guest_halt_poll_shrink is 0, shrink the cpu_halt_poll_us to
> guest_halt_poll_grow_start instead of 0. To disable poll we can set
> guest_halt_poll_ns to 0.
>
> If user wrongly set guest_halt_poll_grow_start > guest_halt_poll_ns > 0,
> guest_halt_poll_ns take precedency and poll time is a fixed value of
> guest_halt_poll_ns.
>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>
> ---
> drivers/cpuidle/governors/haltpoll.c | 28 +++++++++++++---------------
> 1 file changed, 13 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c
> index 660859d..4a39df4 100644
> --- a/drivers/cpuidle/governors/haltpoll.c
> +++ b/drivers/cpuidle/governors/haltpoll.c
> @@ -97,32 +97,30 @@ static int haltpoll_select(struct cpuidle_driver *drv,
>
> static void adjust_poll_limit(struct cpuidle_device *dev, unsigned int block_us)
> {
> - unsigned int val;
> + unsigned int val = dev->poll_limit_ns;
Not necessary to initialize it here.
> u64 block_ns = block_us*NSEC_PER_USEC;
>
> /* Grow cpu_halt_poll_us if
> - * cpu_halt_poll_us < block_ns < guest_halt_poll_us
> + * cpu_halt_poll_us < block_ns <= guest_halt_poll_us
You could update the comment to say "dev->poll_limit_ns" instead of
"cpu_halt_poll_us" while at it.
> */
> - if (block_ns > dev->poll_limit_ns && block_ns <= guest_halt_poll_ns) {
> + if (block_ns > dev->poll_limit_ns && block_ns <= guest_halt_poll_ns &&
> + guest_halt_poll_grow)
The "{" brace is still needed as per the coding style and I'm not sure why
to avoid guest_halt_poll_grow equal to zero here?
> val = dev->poll_limit_ns * guest_halt_poll_grow;
> -
> - if (val < guest_halt_poll_grow_start)
> - val = guest_halt_poll_grow_start;
> - if (val > guest_halt_poll_ns)
> - val = guest_halt_poll_ns;
> -
> - dev->poll_limit_ns = val;
> - } else if (block_ns > guest_halt_poll_ns &&
> - guest_halt_poll_allow_shrink) {
> + else if (block_ns > guest_halt_poll_ns &&
> + guest_halt_poll_allow_shrink) {
> unsigned int shrink = guest_halt_poll_shrink;
>
> - val = dev->poll_limit_ns;
> if (shrink == 0)
> - val = 0;
> + val = guest_halt_poll_grow_start;
That's going to be corrected below, so the original code would be fine.
> else
> val /= shrink;
Here you can do
val = dev->poll_limit_ns / shrink;
> - dev->poll_limit_ns = val;
> }
> + if (val < guest_halt_poll_grow_start)
> + val = guest_halt_poll_grow_start;
Note that guest_halt_poll_grow_start is in us (as per the comment next to its
definition and the initial value). That is a bug in the original code too,
but anyway.
> + if (val > guest_halt_poll_ns)
> + val = guest_halt_poll_ns;
> +
> + dev->poll_limit_ns = val;
> }
>
> /**
>
