Re: ext3 writepages ?

[Sonny Rao <sonny@burdell.org>]

On Tue, Feb 08, 2005 at 12:38:08AM -0500, Sonny Rao wrote:
> On Mon, Feb 07, 2005 at 06:33:51PM -0700, Andreas Dilger wrote:
> > On Feb 03, 2005  15:50 -0500, Sonny Rao wrote:
> > > Well, from what I can tell, my patch doesn't seem to make much of a
> > > difference in write throughput other than allowing multi-page bios to
> > > be sent down and cutting down on buffer_head usage.
> > 
> > Even if it doesn't make a difference in performance, it might reduce the
> > CPU usage.  Did you check that at all?
> 
> No I didn't, I'll check that out and post back.
> 
> Sonny

Ok, I take it back, on a raid device I saw a significant increase in
throughput and approximately equal cpu utilization.   I was comparing
the wrong data points before.. oops.

Sequential overwrite went from 75.6 MB/sec to 87.7 MB/sec both with an
average CPU utilization of 73% for both.

So, I see a 16% improvement in throughput for this test case and a
corresponding increase in efficiency. 

Although, after reading what SCT wrote about writepage and writepages
needing to have a transaction handle, in some cases, that might  make
the proper writepages code significantly more complex than my two-bit
hack.  Still, I think it's worth it.

Sonny