* Kconfig help entry for CONFIG_PARAVIRT_SPINLOCK
@ 2013-10-15 21:45 Sander Eikelenboom
2013-10-16 2:59 ` Raghavendra K T
0 siblings, 1 reply; 2+ messages in thread
From: Sander Eikelenboom @ 2013-10-15 21:45 UTC (permalink / raw)
To: Raghavendra K T; +Cc: linux-kernel
Hi Raghavendra,
Since the ticketlock series have landed in this mergewindow (thanks :-) ) the
help accompanying the Kconfig entry doesn't seem to reflect the current state well.
- Wasn't the whole purpose of the ticketlock series to mitigate this 5% performance hit to something
far less, so distro kernels could enable this for their normal kernels ?
I don't have the exact performance figures though.
- Perhaps the suggestion to enable this for supported hypervisors (Xen and KVM ?) could be added ?
--
Sander
CONFIG_PARAVIRT_SPINLOCKS:
Paravirtualized spinlocks allow a pvops backend to replace the
spinlock implementation with something virtualization-friendly
(for example, block the virtual CPU rather than spinning).
Unfortunately the downside is an up to 5% performance hit on
native kernels, with various workloads.
If you are unsure how to answer this question, answer N.
Symbol: PARAVIRT_SPINLOCKS [=y]
Type : boolean
Prompt: Paravirtualization layer for spinlocks
Location:
-> Processor type and features
-> Linux guest support (HYPERVISOR_GUEST [=y])
-> Enable paravirtualization code (PARAVIRT [=y])
Defined at arch/x86/Kconfig:632
Depends on: HYPERVISOR_GUEST [=y] && PARAVIRT [=y] && SMP [=y]
Selects: UNINLINE_SPIN_UNLOCK [=y]
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Kconfig help entry for CONFIG_PARAVIRT_SPINLOCK
2013-10-15 21:45 Kconfig help entry for CONFIG_PARAVIRT_SPINLOCK Sander Eikelenboom
@ 2013-10-16 2:59 ` Raghavendra K T
0 siblings, 0 replies; 2+ messages in thread
From: Raghavendra K T @ 2013-10-16 2:59 UTC (permalink / raw)
To: Sander Eikelenboom; +Cc: linux-kernel
On 10/16/2013 03:15 AM, Sander Eikelenboom wrote:
> Hi Raghavendra,
>
> Since the ticketlock series have landed in this mergewindow (thanks :-) ) the
> help accompanying the Kconfig entry doesn't seem to reflect the current state well.
>
> - Wasn't the whole purpose of the ticketlock series to mitigate this 5% performance hit to something
> far less, so distro kernels could enable this for their normal kernels ?
> I don't have the exact performance figures though.
>
> - Perhaps the suggestion to enable this for supported hypervisors (Xen and KVM ?) could be added ?
You are right. Thanks. I 'll send the patch to change the config text
soon.
^ permalink raw reply [flat|nested] 2+ messages in thread
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