| Message ID | tencent_2ACBECB5B8EF2442CE608CE48F8E6131CC09@qq.com (mailing list archive) |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
| Series | drivers/cpuidle: Fix guest_halt_poll_ns failed to take effect | expand |
On Fri, Jun 28, 2024 at 11:01 AM ysay <570260087@qq.com> wrote: > > From: ysay <ysaydong@gmail.com> > > When guest_halt_poll_allow_shrink=N,setting guest_halt_poll_ns > from a large value to 0 does not reset the CPU polling time, > despite guest_halt_poll_ns being intended as a mandatory maximum > time limit. > > The problem was situated in the adjust_poll_limit() within > drivers/cpuidle/governors/haltpoll.c:79. > > Specifically, when guest_halt_poll_allow_shrink was set to N, > resetting guest_halt_poll_ns to zero did not lead to executing any > section of code that adjusts dev->poll_limit_ns. > > The issue has been resolved by relocating the check and assignment for > dev->poll_limit_ns outside of the conditional block. > This ensures that every modification to guest_halt_poll_ns > properly influences the CPU polling time. > > Signed-off-by: ysay <ysaydong@gmail.com> This should carry a Fixes: tag pointing to the commit fixed by it. Also, is it -stable material? > --- > drivers/cpuidle/governors/haltpoll.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c > index 663b7f164..99c6260d7 100644 > --- a/drivers/cpuidle/governors/haltpoll.c > +++ b/drivers/cpuidle/governors/haltpoll.c > @@ -78,26 +78,22 @@ static int haltpoll_select(struct cpuidle_driver *drv, > > static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns) > { > - unsigned int val; > + unsigned int val = dev->poll_limit_ns; > > /* Grow cpu_halt_poll_us if > * cpu_halt_poll_us < block_ns < guest_halt_poll_us > */ > if (block_ns > dev->poll_limit_ns && block_ns <= guest_halt_poll_ns) { > - val = dev->poll_limit_ns * guest_halt_poll_grow; > + val *= 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; > > trace_guest_halt_poll_ns_grow(val, dev->poll_limit_ns); > - dev->poll_limit_ns = val; > } 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; > } else { > @@ -108,8 +104,12 @@ static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns) > } > > trace_guest_halt_poll_ns_shrink(val, dev->poll_limit_ns); > - dev->poll_limit_ns = val; > } > + > + if (val > guest_halt_poll_ns) > + val = guest_halt_poll_ns; > + > + dev->poll_limit_ns = val; > } > > /** > -- > 2.43.5 > >
diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c index 663b7f164..99c6260d7 100644 --- a/drivers/cpuidle/governors/haltpoll.c +++ b/drivers/cpuidle/governors/haltpoll.c @@ -78,26 +78,22 @@ static int haltpoll_select(struct cpuidle_driver *drv, static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns) { - unsigned int val; + unsigned int val = dev->poll_limit_ns; /* Grow cpu_halt_poll_us if * cpu_halt_poll_us < block_ns < guest_halt_poll_us */ if (block_ns > dev->poll_limit_ns && block_ns <= guest_halt_poll_ns) { - val = dev->poll_limit_ns * guest_halt_poll_grow; + val *= 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; trace_guest_halt_poll_ns_grow(val, dev->poll_limit_ns); - dev->poll_limit_ns = val; } 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; } else { @@ -108,8 +104,12 @@ static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns) } trace_guest_halt_poll_ns_shrink(val, dev->poll_limit_ns); - dev->poll_limit_ns = val; } + + if (val > guest_halt_poll_ns) + val = guest_halt_poll_ns; + + dev->poll_limit_ns = val; } /**