[linuxppc-release] [PATCH 1/2] powerpc, e5500: add networking to defconfig

[Li Yang-R58472]

>Subject: Re: [linuxppc-release] [PATCH 1/2] powerpc, e5500: add networking
>to defconfig
>
>On Thu, 12 May 2011 10:31:08 -0500
>Scott Wood <scottwood at freescale.com> wrote:
>
>> On Thu, 12 May 2011 01:11:03 -0500
>> Li Yang-R58472 <R58472 at freescale.com> wrote:
>>
>> > >diff --git a/arch/powerpc/configs/e55xx_smp_defconfig
>> > >b/arch/powerpc/configs/e55xx_smp_defconfig
>> > >index 9fa1613..f4c5780 100644
>> > >--- a/arch/powerpc/configs/e55xx_smp_defconfig
>> > >+++ b/arch/powerpc/configs/e55xx_smp_defconfig
>> > >@@ -6,10 +6,10 @@ CONFIG_NR_CPUS=2
>> > > CONFIG_EXPERIMENTAL=y
>> > > CONFIG_SYSVIPC=y
>> > > CONFIG_BSD_PROCESS_ACCT=y
>> > >+CONFIG_SPARSE_IRQ=y
>> >
>> > Hi Scott,
>> >
>> > I remember in previous testing that this option has a negative effect
>on performance.  Do we really need it to be enabled?
>>
>> I didn't change this setting, it just moved due to running it through
>> savedefconfig.
>
>What was the performance impact?

It adds CPU cycles to the interrupt handling path.  Will cause performance drop for benchmarks with large amount of interrupts such as IP forwarding.

- Leo