NFS and kernel cache
Tony Nelson
tonynelson at georgeanelson.com
Thu Dec 21 16:24:19 UTC 2006
At 8:14 AM -0600 12/21/06, Chris Adams wrote:
>Once upon a time, Les <hlhowell at pacbell.net> said:
>> Ethernet only works well when the network is utilized about 50%.
>
>I'm familiar with how Ethernet works, and this is not Ethernet that is a
>problem. Properly configured switched Ethernet can work without errors
>at much more than 50% (I do that every day). Gigabit Ethernet should
>run much faster than 200Mbps. When I ran a similar test with a Fast
>Ethernet interface, I saw similar "stuttering" behavior, but it still
>averaged around 70-80Mbps.
>
>There is no router in my problem setup; this is two systems connected to
>a switch (not a hub). Neither is running anything else (one is booted
>in rescue mode). Both systems show full duplex 1000Mbps link with flow
>control enabled (both have tg3 chips). I was going to try jumbo frames
>to see what difference that made, but one system doesn't support jumbo
>frames.
>
>The fact that Linux stops sending on the network sometimes and stops
>reading the hard drive other times points directly to how the kernel is
>caching writes to NFS (but I can't tell if it is the filesystem layer or
>the network stack).
Copy /dev/zero from each machine to the other, simultaneously? That would
eliminate all of NFS, leaving mostly the kernel.
--
____________________________________________________________________
TonyN.:' The Great Writ <mailto:tonynelson at georgeanelson.com>
' is no more. <http://www.georgeanelson.com/>
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