Re: NFS performance problems on vxWorks

[Andrew Johnson <anj@aps.anl.gov>]

Dirk,

Dirk Zimoch wrote:
> our vxWorks IOCs mount their boot directory, auto-save-and-restore 
> directory and data aquisition directory via NFS.
>
> Now, I noticed a very poor performance on several IOCs. Test 
...
> When only vxWorks is running but not EPICS, it seems to be ok. If an 
> empty EPICS (no records) is running, there few errors. The problem does 
> not depend on the EPICS version (I tried 3.13.2 and 3.13.9). The idle 
> time of the ioc is about 80%.

The NFS protocol version supported by vxWorks uses UDP packets for data 
transfer, and is not as efficient at handling dropped packets as TCP is. 
In your case, I suspect that your IOCs are dropping input packets from the 
network, which causes the 5 second NFS delays.

Since your IOC has lots of idle time available, you should be able to 
resolve this by just increasing the size of the network input buffer pool, 
which is usually one of the parameters in the vxWorks END configuration 
string - have a look in your sysEnd.c file [or wherever the xxxEndLoad() 
routine is called in your BSP] and increase the number of read buffers.

- Andrew
--
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the sunset you made last night.  That was really cool. - Caro