mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-09-29 22:02:02 +00:00
Code Issues Releases Wiki Activity

KVM: x86: reduce default value of halt_poll_ns parameter

Browse source 
Windows lets applications choose the frequency of the timer tick,
and in Windows 10 the maximum rate was changed from 1024 Hz to
2048 Hz.  Unfortunately, because of the way the Windows API
works, most applications who need a higher rate than the default
64 Hz will just do

   timeGetDevCaps(&tc, sizeof(tc));
   timeBeginPeriod(tc.wPeriodMin);

and pick the maximum rate.  This causes very high CPU usage when
playing media or games on Windows 10, even if the guest does not
actually use the CPU very much, because the frequent timer tick
causes halt_poll_ns to kick in.

There is no really good solution, especially because Microsoft
could sooner or later bump the limit to 4096 Hz, but for now
the best we can do is lower a bit the upper limit for
halt_poll_ns. :-(

Reported-by: Jon Panozzo <jonp@lime-technology.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-03-29 17:56:57 +02:00
parent a2b5c3c0c8
commit 14ebda3394
1 changed files with 1 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
arch/x86/include/asm/kvm_host.h
View file

@ -43,7 +43,7 @@
#define KVM_PIO_PAGE_OFFSET 1 #define KVM_PIO_PAGE_OFFSET 1
#define KVM_COALESCED_MMIO_PAGE_OFFSET 2 #define KVM_COALESCED_MMIO_PAGE_OFFSET 2
#define KVM_HALT_POLL_NS_DEFAULT 500000 #define KVM_HALT_POLL_NS_DEFAULT 400000
#define KVM_IRQCHIP_NUM_PINS KVM_IOAPIC_NUM_PINS #define KVM_IRQCHIP_NUM_PINS KVM_IOAPIC_NUM_PINS