Hi Robert,
Yes that is correct about RSC vs. LRO. Have you tried turning of RSC on 82599?
ethtool -K lro off ethX
Also how about if you disable DCB? Does that have impact on latency?
Also could you please send us following after loading the driver:
Output from:
dmesg
lspci -vvv
Thanks,
Stephen
-----Original Message-----
From: Torres, Robert (CCL) [rtor...@carnival.com<mailto:rtor...@carnival.com>]
Sent: Thursday, November 08, 2012 03:04 PM Pacific Standard Time
To: 'e1000-de...@lists.sf.net'
Subject: [E1000-devel] Poor Read Performance with 82599EB on Red Hat Linux
Getting two distinctive behaviors from two RHEL 5 servers. Seems the host with
the 82599 NICs reports significant latency when read requests surpass 32KB. The
host with the 82598 NICs does not demonstrate this behavior. It's our
understanding that the two NIC adapters perform different offload capability.
The 82599-based adapters support HW based receive side coalescing (RSC) which
can merge multiple frames from the same IPv4 TCP/IP flow into a single
structure that can span one or more descriptors, while the 82598-based adapter
rely on driver side LRO for aggregation.
DCB is enabled on the arrays ports and don't know if this has any relevance to
the above issue.
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