Freebsd Theme Song

[Kris Kennaway]

On Sat, Dec 10, 2005 at 05:34:23PM -0600, David Kelly wrote:

> >But anyway, FreeBSD 6.0 is hugely superior to 5.4 and 4.11 in
> >filesystem performance.  I have been measuring this carefully for the
> >past couple of months and hope to have the paper out soon.
> 
> For instance in 5.4 the fastest I could write to my /usr/ partition  
> on a simple default-partitioned UDMA100 drive was 16 MB/sec with a  
> 2.8 GHz P4 while it was capable of reading at over 40 MB/sec. Saw  
> RELENG_6 writing on that partition at over 40 MB/sec recently.  
> Unscientific tests using "systat -v" and moving big files.
> 
> A gvinum striped volume on two SATA150 drives routinely produces 70  
> MB/sec reads and writes.

On this amr array with 4 disks, write performance is up to 150 MB/sec
on the device with multiple processes writing to the filesystem.  This
makes it a good testbed because there's a lot of room to observe
scaling under varying loads.

> Its nice that FreeBSD is now close to the hardware's performance.

> One  
> nit is that with such a large sustained access other small accesses  
> are starved. Probably a scheduler issue, and I'm sure the scheduler  
> is being worked on.

Yes, I've noticed that too.  It also occurs in 4.11 and 5.4, but is
about 50% less severe on 4.11.  The ULE scheduler is much better in
this respect, but processes run about 5-20% slower under most loads.

Kris
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