On 18.09.2013, at 02:33, Guillaume Gardet wrote:

Le 16/09/2013 16:17, Alexander Graf a écrit :

...

Hey,

Am 16.09.2013 um 07:12 schrieb Guillaume Gardet :

...

Hi,

I would like to enable a kernel-desktop for ARM, especially for GFX images.

I modified kernel-default by using CONFIG_PREEMPT instead of CONFIG_PREEMPT_NONE. Couldn't we just make preempt_desktop the default for armv7?

It could save us a kernel flavour build but CONFIG_PREEMPT_NONE would be better for servers (better dry performances) and CONFIG_PREEMPT would be better for desktop interfaces (less latency).

Well, is the difference significant? If the loss in performance for server style workloads is negligible, why not always enable preemption? Alex -- To unsubscribe, e-mail: opensuse-arm+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-arm+owner@opensuse.org

Am 20.09.2013 um 02:37 schrieb Guillaume Gardet :

Le 20/09/2013 05:34, Alexander Graf a écrit :

...

On 18.09.2013, at 02:33, Guillaume Gardet wrote:

...

Le 16/09/2013 16:17, Alexander Graf a écrit :

...

Hey,

Am 16.09.2013 um 07:12 schrieb Guillaume Gardet :

...

Hi,

I would like to enable a kernel-desktop for ARM, especially for GFX images.

I modified kernel-default by using CONFIG_PREEMPT instead of CONFIG_PREEMPT_NONE. Couldn't we just make preempt_desktop the default for armv7? It could save us a kernel flavour build but CONFIG_PREEMPT_NONE would be better for servers (better dry performances) and CONFIG_PREEMPT would be better for desktop interfaces (less latency). Well, is the difference significant? If the loss in performance for server style workloads is negligible, why not always enable preemption?

I did not benchmark it, but I guess there is a significant difference, otherwise, openSUSE x86 kernels would not have 2 flavours. Maybe, we should ask on -kernel ML?

Is there anyone having opinion/benchmark about that?

One thing is sure, preempt gives a better desktop user experience.

IIRC the main driver behind preempt_none is SLES where 1% performance counts a lot. For us it shouldn't really matter too much and I'd prefer to keep things simple for everyone rather than optimized. Alex

Guillaume

-- To unsubscribe, e-mail: opensuse-arm+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-arm+owner@opensuse.org