| Message ID | 20240111135950.17016-1-parshuram.sangle@intel.com |
|---|---|
| State | Accepted |
| Commit | 496d0a648509bce665a85e19a871375dfe4c8f2e |
| Headers | show |
| Series | cpuidle: do not shrink guest poll_limit_ns below grow_start | expand |
On Thu, Jan 11, 2024 at 07:29:50PM +0530, Parshuram Sangle wrote: > While adjusting guest halt poll limit, grow block starts at > guest_halt_poll_grow_start without taking intermediate values. > Similar behavior is expected while shrinking the value. This > avoids short interval values which are really not required. > > VCPU1 trace (guest_halt_poll_shrink equals 2): > > VCPU1 grow 10000 > VCPU1 shrink 5000 > VCPU1 shrink 2500 > VCPU1 shrink 1250 > VCPU1 shrink 625 > VCPU1 shrink 312 > VCPU1 shrink 156 > VCPU1 shrink 78 > VCPU1 shrink 39 > VCPU1 shrink 19 > VCPU1 shrink 9 > VCPU1 shrink 4 > > Similar change is done in KVM halt poll flow with below patch: > Link: https://lore.kernel.org/kvm/20211006133021.271905-3-sashal@kernel.org/ > > Co-developed-by: Rajendran Jaishankar <jaishankar.rajendran@intel.com> > Signed-off-by: Rajendran Jaishankar <jaishankar.rajendran@intel.com> > Signed-off-by: Parshuram Sangle <parshuram.sangle@intel.com> > --- > drivers/cpuidle/governors/haltpoll.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c > index 1dff3a52917d..663b7f164d20 100644 > --- a/drivers/cpuidle/governors/haltpoll.c > +++ b/drivers/cpuidle/governors/haltpoll.c > @@ -98,10 +98,15 @@ static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns) > unsigned int shrink = guest_halt_poll_shrink; > > val = dev->poll_limit_ns; > - if (shrink == 0) > + if (shrink == 0) { > val = 0; > - else > + } else { > val /= shrink; > + /* Reset value to 0 if shrunk below grow_start */ > + if (val < guest_halt_poll_grow_start) > + val = 0; > + } > + > trace_guest_halt_poll_ns_shrink(val, dev->poll_limit_ns); > dev->poll_limit_ns = val; > } > -- > 2.17.1 > > > Looks good. Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
On Thu, Feb 1, 2024 at 8:56 PM Marcelo Tosatti <mtosatti@redhat.com> wrote: > > On Thu, Jan 11, 2024 at 07:29:50PM +0530, Parshuram Sangle wrote: > > While adjusting guest halt poll limit, grow block starts at > > guest_halt_poll_grow_start without taking intermediate values. > > Similar behavior is expected while shrinking the value. This > > avoids short interval values which are really not required. > > > > VCPU1 trace (guest_halt_poll_shrink equals 2): > > > > VCPU1 grow 10000 > > VCPU1 shrink 5000 > > VCPU1 shrink 2500 > > VCPU1 shrink 1250 > > VCPU1 shrink 625 > > VCPU1 shrink 312 > > VCPU1 shrink 156 > > VCPU1 shrink 78 > > VCPU1 shrink 39 > > VCPU1 shrink 19 > > VCPU1 shrink 9 > > VCPU1 shrink 4 > > > > Similar change is done in KVM halt poll flow with below patch: > > Link: https://lore.kernel.org/kvm/20211006133021.271905-3-sashal@kernel.org/ > > > > Co-developed-by: Rajendran Jaishankar <jaishankar.rajendran@intel.com> > > Signed-off-by: Rajendran Jaishankar <jaishankar.rajendran@intel.com> > > Signed-off-by: Parshuram Sangle <parshuram.sangle@intel.com> > > --- > > drivers/cpuidle/governors/haltpoll.c | 9 +++++++-- > > 1 file changed, 7 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c > > index 1dff3a52917d..663b7f164d20 100644 > > --- a/drivers/cpuidle/governors/haltpoll.c > > +++ b/drivers/cpuidle/governors/haltpoll.c > > @@ -98,10 +98,15 @@ static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns) > > unsigned int shrink = guest_halt_poll_shrink; > > > > val = dev->poll_limit_ns; > > - if (shrink == 0) > > + if (shrink == 0) { > > val = 0; > > - else > > + } else { > > val /= shrink; > > + /* Reset value to 0 if shrunk below grow_start */ > > + if (val < guest_halt_poll_grow_start) > > + val = 0; > > + } > > + > > trace_guest_halt_poll_ns_shrink(val, dev->poll_limit_ns); > > dev->poll_limit_ns = val; > > } > > -- > > 2.17.1 > > > > > > > > Looks good. > > Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Applied as 6.9 (with a minor change in the subject), thanks!
diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c index 1dff3a52917d..663b7f164d20 100644 --- a/drivers/cpuidle/governors/haltpoll.c +++ b/drivers/cpuidle/governors/haltpoll.c @@ -98,10 +98,15 @@ static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns) unsigned int shrink = guest_halt_poll_shrink; val = dev->poll_limit_ns; - if (shrink == 0) + if (shrink == 0) { val = 0; - else + } else { val /= shrink; + /* Reset value to 0 if shrunk below grow_start */ + if (val < guest_halt_poll_grow_start) + val = 0; + } + trace_guest_halt_poll_ns_shrink(val, dev->poll_limit_ns); dev->poll_limit_ns = val; }