FreeBSD's UFS vs Ext4

alex alex at
Mon Feb 8 04:46:15 UTC 2010

Pieter de Goeje wrote:
> The fact that the limit is 86MB/sec (which is very low for a raid0 array) 
> makes me think the box suffers from sub optimal network performance during a 
> simple stream test like yours. This could be due to FreeBSD having a poor 
> network driver for your particular NIC or could be due to insufficient tuning 
> of the TCP parameters for this particular test.
Hi Pieter.

You are right about there being a number of possibilities, however:

*The same machine, which over the years has had a number of revisions of 
freebsd on it (have buildworlded the thing from 7-> 7.1 -> 7.2 -> 8), 
the performance was always roughly the same amongst the versions, I dont 
agree with the possibility of the ftp server being 'slow' as I am the 
only person who copies data to that machine, and the machine is always 
under a very low (almost non existent) load.

* Network card is an Intel Pro 1000, on the server. This is a PCI card 
(not pci-e), so I believe PCI bus bandwidth limitations may be 
responsible for me not being able to achieve the maximum 100MB/s network 
rate (as you mention that 86MB/s is slow for raid0)

* The intel network card driver on freebsd and linux are both fairly 
rock solid and well written. I dont see it being an issue with NIC 
drivers (they are not vastly different).

* Both OS's were stock standard installs, no jumbo frames enabled, no 
fiddling with sysctl network values.

I am happy with 86MB/s anyway, It's a huge improvement of the 60MB/s 
barrier I could never get past when that machine was running FreeBSD. To 
get the rest of the speed, I'd probably have to install a pci-e card on 
the server.

I do suspect personally that the ext4 filesystem is the reason for the 
difference here, since ext4 has a number of features such as deferred 
disk writes etc. Even deleting a large file off that raid array I can 
see a difference, prior to reformatting, i deleted a 190GB file off the 
raid, under UFS the delete took quite some time (well over 10 seconds), 
under ext4 the deletion of the same size file took about 3 seconds.

But what I said with ext4 being faster then the aging UFS still rings 
true in my mind, look at the recent Phoronix benchmarks for yourself and 
see (10 pages of benchmarks). 
(skip to page 7 of the benchmarks if you want to see the I/O stuff 
relating to disk performance)

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