RE: 3Ware 9550SX and latency/system responsiveness

["Ross S. W. Walker" <rwalker@xxxxxxxxxxxxx>]

Simon Banton wrote:
> 
> At 10:36 -0400 25/9/07, Ross S. W. Walker wrote:
> >Post the modinfo <driver name> to the list just in case somebody
> >else knows of any issues with the version you are running.
> 
> This is from RHEL5 - it's the driver that comes built-in:
> 
> [root@serv1 ~]# modinfo 3w-9xxx
> filename:       
> /lib/modules/2.6.18-8.el5/kernel/drivers/scsi/3w-9xxx.ko
> version:        2.26.02.007
> license:        GPL
> description:    3ware 9000 Storage Controller Linux Driver
> author:         AMCC
> srcversion:     029473DD729D96D687985E4
> alias:          pci:v000013C1d00001003sv*sd*bc*sc*i*
> alias:          pci:v000013C1d00001002sv*sd*bc*sc*i*
> depends:        scsi_mod
> vermagic:       2.6.18-8.el5 SMP mod_unload 686 REGPARM 
> 4KSTACKS gcc-4.1
> 
> The overall responsiveness of the system under benchmarking when 
> running RHEL5 is somewhat better than that when running CentOS 4.5.

Off of 3ware's support site I was able to download and compile the
latest stable release which has this modinfo:

[root@mfg-nyc-iscsi1 driver]# modinfo 3w-9xxx.ko
filename:       3w-9xxx.ko
version:        2.26.06.002-2.6.18
license:        GPL
description:    3ware 9000 Storage Controller Linux Driver
author:         AMCC
srcversion:     7F428E7BA74EAFF0FF137E2
alias:          pci:v000013C1d00001004sv*sd*bc*sc*i*
alias:          pci:v000013C1d00001003sv*sd*bc*sc*i*
alias:          pci:v000013C1d00001002sv*sd*bc*sc*i*
depends:        scsi_mod
vermagic:       2.6.20-1.2320.fc5smp SMP mod_unload 686 4KSTACKS

I compiled it on a fc5 box, but that shouldn't matter.

As far as the "responsiveness" is concerned, the 2.6.18 kernel made
some substantial improvements to the "cfq" io scheduler that helped
with interactive user experience. If you are using the box as a
server though I would try the "deadline" or "noop" scheduler with
this card as you may see substantial performance improvements with
these schedulers and this card.

Try setting the io scheduler to "deadline" and re-run the benchmarks
to see what I mean.

-Ross

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