Re: ixg(4) performances

[Emmanuel Dreyfus <manu%netbsd.org@localhost>]

On Tue, Aug 26, 2014 at 12:57:37PM +0000, Christos Zoulas wrote:
> >I also found this page that tackles the same problem on Linux:
> >http://dak1n1.com/blog/7-performance-tuning-intel-10gbe

It seems that page describe a slightly different model.
Intel 82599 datasheet is available here:
http://www.intel.fr/content/www/fr/fr/ethernet-controllers/82599-10-gbe-controller-datasheet.html

No reference to MMRBC in this document, but I understand "Max Read Request
Size" is the same thing. Page 765 tells us about register A8, bits 12-14
that should be set to 100.
pcictl /dev/pci5 read -d 0 -f 1 0x18 tells me the value 0x00092810

I tried this command:
pcictl /dev/pci5 write -d 0 -f 1 0x18 0x00094810 

Further pcictl read suggests it works as the new value is returned.
However it gives no performance improvement. This means that I 
misunderstood what this register is about, or how to change it (byte order?).

Or the performance are constrained by something unrelated. In the blog 
post cited above, the poster acheived more than 5 Gb/s before touching
MMRBC, while I am stuck at 2,7 GB/s. Any new idea welcome.

-- 
Emmanuel Dreyfus
manu%netbsd.org@localhost