c6145 pcie max payload

Stijn De Weirdt stijn.deweirdt at ugent.be
Thu Jul 21 09:12:52 CDT 2011


i tried the patch from the RFC v7
(http://marc.info/?l=linux-pci&m=131119372412927&w=2)

this is the output of the mezzanine raid controller (SAS2008 PCI-Express
Fusion-MPT SAS-2 [Falcon] (rev 03))

pci 00002:00.0: Dev MPS 128 MPSS 4096 MRRS 512
pci_bus 0000:02: Bus MPSS 128
pci 0000:02:00.0: Dev MPS 128 MPSS 128 MRRS 128

the limiting factor is the MPS of the bus (i assume the parent in the
pce tree, in this case an RD890 chip), so this patch is either wrong (or
i can't apply it properly) or not a solution to get higher payload size.

i'll try to follow it up...

stijn
> This discussion is still happening upstream and a few Dell engineers have been involved in this effort.. http://marc.info/?l=linux-pci&m=131066890717612&w=2
> 
> Unfortunately I believe there is no way to change it via sysfs or some other parameter at the moment.
> 
> Once the features gets in upstream we should be able to get it into our supported OSes as well.
> 
> Shyam Iyer
> Linux Engineering
> 
> -----Original Message-----
> From: linux-poweredge-bounces-Lists On Behalf Of Stijn De Weirdt
> Sent: Saturday, July 16, 2011 9:18 AM
> To: linux-poweredge-Lists
> Subject: c6145 pcie max payload
> 
> hi all,
> 
> we have a number of c6145 machines that we use in HPC context. in order
> to get maximum performance out of the nodes (and the IB network in
> particular), we would like to set the maximum pcie payload to 256 or 512
> bytes. current maximum value is 128 bytes.
> 
> normally, this is an option in the bios, but i don't find it (i don't
> think the option is there). does anyone know how we could change it? (we
> are using SL6 as OS).
> 
> any feedback is welcome.
> 
> stijn

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http://hasthelhcdestroyedtheearth.com/




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