Huge ubi or ubifs sync slowdown since 2.6.32

[Charles Manning]

Hi All

I've been looking into a ubifs performance regression on linux-omap 2.6.37.

My test is pretty simple, copy a 2Mbyte file and sync.

# sync; date; cp 2Mbyte-file foo; sync; date

On 2.6.32 and earler, the time between the two dates was around 3 seconds.
On linux-omap master it is around 14 seconds. Ouch!

At first I thought the problem was due to changes in the OMAP nand drivers, 
but raw randwrite speed is actually a bit faster. This suggest the finger 
should be pointed at ubi or ubifs.

I then thought that perhaps the layout of my ubinized image might be a 
contributing factor so I erased the partition, ubiformatted and ubimkvoled. 
The problem persisted,

Any suggestions as to what might be broken or how to debug this deeper?

Thanks

Charles