phoronix benchmarks ext4 vs. btrfs

Przemek Klosowski przemek.klosowski at
Fri Mar 9 13:42:36 UTC 2012

On 03/09/2012 01:43 AM, Adam Williamson wrote:
> On Thu, 2012-03-08 at 22:19 -0700, Chris Murphy wrote:
>> I'm not sure how useful 'time' is as a benchmark for file copies.
> Don't file transfers get cached and return to a console as 'complete'
> long before the data is ever written, sometimes?
> I'm pretty sure you sometimes hit the case where you copy 200MB to a USB
> stick, it returns to the console pretty fast, but the light on the stick
> is still flashing, and if you run 'sync', it sits there for quite a
> while before returning to the console, indicating the transfer wasn't
> really complete. So I'm not sure 'time'ing a 'cp' is an accurate test of
> actual final-write-to-device.

That is true---but in that case, we could flush the disks. and then time 
the operation followed by another flush, i.e.:

sync; time (cp ...; sync)

I assume that the old-time Unix superstition of calling sync three times 
no longer applies :)

Perhaps a dedicated disk benchmark like bonnie++ would be a better test, 

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