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[0/2] xen/x86: Optimize timer_irq_works()

Message ID 20230818134441.45586-1-julien@xen.org (mailing list archive)
Headers show
Series xen/x86: Optimize timer_irq_works() | expand

Message

Julien Grall Aug. 18, 2023, 1:44 p.m. UTC 
From: Julien Grall <jgrall@amazon.com>

Hi all,

At the moment timer_irq_works() will always wait 100ms even with
enough ticks elapsed. This is a bit wasteful when most of the HW
should not be buggy.

The admin may also know that their HW is not buggy so they could
decide to skip the full 100ms. Also, looking at Linux changes, it
was pointed out that the timer_irq_works() may always return false
on when using para-virtualized delay. It is not a problem for Xen,
but still it makes sense to provide an option to disable the timer
check.

Patch #1 of the series will add the command line option while patch
#2 will optimize timer_irq_works() for the good case.

Cheers,

Julien Grall (2):
  xen/x86: io_apic: Introduce a command line option to skip timer check
  xen/x86: ioapic: Bail out from timer_irq_works() as soon as possible

 docs/misc/xen-command-line.pandoc |  7 ++++++
 xen/arch/x86/io_apic.c            | 41 ++++++++++++++++++++++---------
 2 files changed, 37 insertions(+), 11 deletions(-)