Netbench results on a linux 4-way system

Goetz Rieger goetz.rieger at
Thu Aug 1 01:00:15 GMT 2002

Hey Andrew,

On Wed, 31 Jul 2002 12:56:04 -0500
Andrew Theurer <habanero at> wrote:

great stuff. As you can think, I have never got the chance to run "real"
netbench-runs. So I am not very familiar with interpreting the results....

Could you publish more data, like the plot throughput against clients? 

Any performance data on Samba/Linux is relevant. ;-)


> I though I'd share some NetBench results on one of our servers.
> Server:
> 4 x 1.5 GHz P4, 256K L3, 32MB L4, 2 GB memory
> 4 x 1Gbps acenic ethernet
> 14 SCSI disks in hardware RAID1 with 128 MB writeback NVRAM
> SuSE 8.0, 2.4.18 kernel
> Samba 2.2.3a
> Ext3 fs
> Clients:
> 48 x 866 MHz PIII running Windows 2000
> Results:
> Baseline				576 Mbps
> ext3 data=writeback		623 Mbps
> samba smblog=1			673 Mbps
> sendfile/zerocopy		801 Mbps
> O(1) scheduler			809 Mbps
> Evenly affined IRQs		800 Mbps *needed to get process affinity correct
> Process affinity			848 Mbps
> /proc/sys/net/hll=764		853 Mbps
> case sens enforced		895 Mbps
> samba spinlocks			912 Mbps
> dcache read copy update 	923 Mbps (also had 5% idle time)
> I have also achieved 1002 Mbps with ext2.
> Some other things I think may be worth investigating:
> gettimeofday().  Samba calls this a lot, one for every reply I think, to
> check for connection timeout.  This means we go into kernel mode every
> single time we call this, something I'd like to avoid.  And I also don't
> think we need the resolution of gettimeofday for this.  How about some
> sort of timer in samba with a 1 second granularity?  I admit I have not
> thought about how to do this, but there's gotta be a way.  
> locking for the samba db.  Spin locks got us a little better than
> flocks, but again I'd rather not go into kernel mode every time.  Has
> anyone considered using Rusty Russell's futexes for this?  
> Hyperthreading.  With 2 physical processors, I can get 25% better
> results!!!  with 4 physical processors, I only get 2% better.  I may be
> running into other bottlenecks on the 4 physical/8 logical CPU case, so
> I hope there is room for improvement.  However there are probably a lot
> more 2-way P4 systems out there than 4-way, so I bet this could really
> benefit a lot of people out there.  
> Anyway, I have a lot of analysis data (kernel profiles mostly) that goes
> along with this stuff if anyone is interested in looking at it  My
> intention was to make some sort of article out of this, so I wanted to
> get some feedback from this list.  Is this stuff interesting or relevant
> to anyone out there?  What else would you like to see in terms of samba
> on linux  performance?  
> Thanks,
> Andrew Theurer

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