From 496d0a648509bce665a85e19a871375dfe4c8f2e Mon Sep 17 00:00:00 2001 From: Parshuram Sangle Date: Thu, 11 Jan 2024 19:29:50 +0530 Subject: [PATCH] cpuidle: haltpoll: do not shrink guest poll_limit_ns below grow_start 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 Signed-off-by: Rajendran Jaishankar Signed-off-by: Parshuram Sangle Reviewed-by: Marcelo Tosatti [ rjw: Subject edits ] Signed-off-by: Rafael J. Wysocki --- 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 1dff3a52917de..663b7f164d202 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; } -- 2.30.2