MXC nand controller performance

[Magnus Lilja]

Hi

2009/8/21 Sascha Hauer <s.hauer at pengutronix.de>:
> On Thu, Aug 20, 2009 at 10:10:27PM +0200, Magnus Lilja wrote:
>> Hi Sascha,
>>
>> 2009/8/20 Sascha Hauer <s.hauer at pengutronix.de>:
>> > Hi,
>> >
>> > Hi recently found out that on my i.MX27 board the mxc nand controller
>> > performance nearly doubles when I disable interrupts. Can anybody
>> > confirm this behaviour, possibly on other i.MXs?
>> > I'm trying to figure out what to do. We could disable interrupts
>> > completely in which case the driver would become simpler. Maybe using
>> > polling mode has other impacts on other workloads, so maybe we want to
>> > add a flag to platform_data instead of disabling interrupts completely.
>>
>> A flag sounds like a good idea.
>>
>> > You can use the following patch to disable interrupts. It is not meant
>> > for inclusion in this form of course.
>>
>> I can give it a try on i.MX31, how do you measure the performance?
>
> I did a 'time cat /dev/mtdblockx > /dev/null' and looked at the time
> needed to mount an ubifs. I haven't done any write tests though.

I did some tests on a i.MX31 Litekit board using a kernel from Linus'
tree a couple of days ago ('time cat /dev/mtdblockx > /dev/null'):
with interrupts: 18s
without interrupts: 13s

No write tests or mounting filesystems were done.

/Magnus