[ofa-general] [PATCH] osm_ucast_ftree.c Allow horizontal links between switches of max rank

[Line.Holen at Sun.COM]

On 06/ 2/09 02:11 PM, Nicolas Morey-Chaisemartin wrote:
> Hi,
> 
> I've just run a few tests with your patch using io_guid_files and reverse_hops and it seems your patch introduces a bug.
> We have a function to calculate the number per link and if I apply this patch it never returns which usually means there is a loop in the routing scheme.
> 
> I have had a quick look at your code.
> One thing I'm not sure of is that when a reverse hop is done you increment both the reverse_hop counter and the current_hops one. Which mean when the hops count is calculate for sw_set_hops it is bigger than it is supposed to be.
> 
> 
> What should probably be done is increment both but only use current_hops to calculate the number of hops done. reverse_hop will only be used to check if there are still reverse_hop credits left or not (which was its original purpose).
> 

I think you are right. current_hops is updated also for reverse hops and should be sufficient.

> By changing the hops count in both call to set_hops_on_remote_sw  to current_hops+1 and not current_hops+1 +2* reverse_hops, routing has no loops but results are different (some links are more loaded).
> I'll run some more tests to see if I can figure this out.
> 

OK. I'll run some tests myself. Please let me know if you find anything suspicious.


Line

> 
> Nicolas
> 
> Le 27/05/2009 12:07, Line.Holen at Sun.COM a écrit :
>> This patch makes it legal to have cross links (horizontal links) between
>> switches at max rank. These switches do have same rank, so hop count cannot
>> be calculated based on rank anymore.
>> The horizontal links are treated as downlinks. Switch A has a downlink to B
>> while B has a downlink to A. Tests on lids and also number of hops makes sure
>> that we don't loop back and forth across the link.
>>
>> Signed-off-by: Frank Olaf Sem-Jacobsen <frankose at simula.no>
>> Signed-off-by: Line Holen <Line.Holen at sun.com>
>>
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