FreeBSD's UFS vs Ext4

[alex]

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).

http://www.phoronix.com/scan.php?page=article&item=freebsd8_benchmarks&num=1 
(skip to page 7 of the benchmarks if you want to see the I/O stuff 
relating to disk performance)