linux-kernel - [PATCH v3 0/3] KVM: Dynamic halt_poll

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Message-ID: <BLU436-SMTP224C138C142B0EFD8A70CEF80600@phx.gbl>
Date:	Wed, 26 Aug 2015 17:14:30 +0800
From:	Wanpeng Li <wanpeng.li@...mail.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
CC:	David Matlack <dmatlack@...gle.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Wanpeng Li <wanpeng.li@...mail.com>
Subject: [PATCH v3 0/3] KVM: Dynamic halt_poll_ns 

v2 -> v3:
 * grow/shrink vcpu->halt_poll_ns by *halt_poll_ns_grow or /halt_poll_ns_shrink
 * drop the macros and hard coding the numbers in the param definitions
 * update the comments "5-7 us"
 * remove halt_poll_ns_max and use halt_poll_ns as the max halt_poll_ns time,
   vcpu->halt_poll_ns start at zero
 * drop the wrappers 
 * move the grow/shrink logic before "out:" w/ "if (waited)"

v1 -> v2:
 * change kvm_vcpu_block to read halt_poll_ns from the vcpu instead of 
   the module parameter
 * use the shrink/grow matrix which is suggested by David
 * set halt_poll_ns_max to 2ms

There is a downside of halt_poll_ns since poll is still happen for idle 
VCPU which can waste cpu usage. This patchset add the ability to adjust 
halt_poll_ns dynamically. 

There are two new kernel parameters for changing the halt_poll_ns:
halt_poll_ns_grow and halt_poll_ns_shrink. The shrink/grow matrix is 
suggested by David: 

if (poll successfully for interrupt): stay the same
  else if (length of kvm_vcpu_block is longer than halt_poll_ns_max): shrink
  else if (length of kvm_vcpu_block is less than halt_poll_ns_max): grow

Wanpeng Li (3):
  KVM: make halt_poll_ns per-VCPU
  KVM: dynamic halt_poll_ns adjustment
  KVM: trace kvm_halt_poll_ns grow/shrink

 include/linux/kvm_host.h   |  1 +
 include/trace/events/kvm.h | 30 ++++++++++++++++++++++++++
 virt/kvm/kvm_main.c        | 52 +++++++++++++++++++++++++++++++++++++++++++---
 3 files changed, 80 insertions(+), 3 deletions(-)

-- 
1.9.1

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