Re: File System Performance results

[Chris Mason <chris.mason@oracle.com>]

On Mon, 2008-10-27 at 09:28 -0500, Steven Pratt wrote:
> Andreas Dilger wrote:
> > On Oct 22, 2008  15:06 -0500, Steven Pratt wrote:
> >   
> >> We have set up a new page which is intended mainly for tracking the  
> >> performance of BTRFS, but in doing so we are testing other filesystems  
> >> as well (ext3, ext4, xfs and jfs).  Thought some people here might find  
> >> the results useful.
> >>
> >>
> >> The main page is here:
> >>
> >> http://btrfs.boxacle.net/

I meant to ask if this is a permanent site for the results?  It might
make sense to add a more generic fsperf.boxacle.net page.

> >>
> >> Information about the machine configuration, tests run, how to reproduce  
> >> the run and link to graphs of all the results are provided off of this  
> >> page.  When looking at any individual test, links are provided to the  
> >> detail output from the tests including iostat, mpstat, oprofile data and  
> >> more.
> >>     
> >
> > Steve,
> > thanks for posting the numbers.  They are definitely interesting.  On
> > the surface, ext4 is doing quite well overall (yay!),
> Yes, that was good news.  Along these lines if there is anything else we 
> can do to help out ext4, just let us know.
> 
> >  but the important
> > point to realize is that btrfs is also providing a lot of extra function
> > under the covers so it isn't necessarily a clear-cut answer on which one
> > to pick.
> >
> > The extra CPU cost of btrfs will become increasingly irrelevant in the
> > future I think.
> >   
> While I agree that CPU usage is becoming less and less of an issue, I 
> think that at this point in the development cycle of btrfs, we still 
> need to take a hard look at any areas where cpu usage is excessive, and 
> see if we can keep that to a minimum.

Very true, especially performance results with checksumming off (like
the nodatacow results for random writes).

>   This is the main reason we did 
> runs without checksumming, so we could see a better apple to apple 
> comparison, not because it is not a useful feature.  It will be very 
> interesting to see how much HW checksumming changes this with Nehelam.

See the btrfs crc header file for the #define to enable the hw assist
mode if you're got the hardware that can do it.  In my runs here, it
makes the checksumming free aside from the time spent storing the extra
metadata.

-chris