> > > BTW, is this change results noticable effect?
> > 
> > no human noticable effects, i think. :-)
> 
> I'm interested in the number of i/o issued, espcially on low memery
> envronment.

total number of i/o shouldn't be changed by this.
it might be different very slightly if we have lower layer clustering, though.

number of concurrent (pending )i/o might be increased, of course.
do you mean, it can pressure memory?

YAMAMOTO Takashi