[openib-general] Repost: AIO SDP and ttcp.aio: Event errors

[Steven Wooding]

1. OK. That's fair enough. I'll give that ago.

2. Yeah, it also occurs for large values of -n, say 10000.

3. Great.

4. Yeah, the times are small as I'm only doing short runs (-n 1000) to 
avoid the -32/-104 errors. I'll try pushing -n up a bit.

Thanks Libor,

Steve.


Libor Michalek wrote:

>On Tue, Apr 12, 2005 at 09:08:15PM +0100, Steven Wooding wrote:
>  
>
>>Hi,
>>
>>I have been putting ttcp.aio through its paces and have a few questions.
>>
>>1. When -l is larger than 131072 I get an Event error <-22> on the transmit
>>side and no data to transferred. Changing values of -n and -a do not make
>>any difference.
>>    
>>
>
>  The FMRs need to be sized at initialization time. The code currently
>picks 128K as the size for the FMRs, and does not support an AIO operation
>that would span multiple FMRs. If you want to try larger AIO operations
>with the current code you will need to recompile SDP with a larger FMR
>size, which is determined by the constant SDP_IOCB_SIZE_MAX in sdp_iocb.h
>It's been a while since I've last tried this, if you try it and have
>problems let me know.
>
>  
>
>>2. When using a value of 1 for -a (so I suppose this is non-aio), I get an
>>Event error of <-32> on the transmit side and an <-104> on the receiver end.
>>Only some of the data is transferred.
>>    
>>
>
>  I'll look into this, I'm seeing a problem on longer runs myself. With a
>value of 1 for -a it still uses aio, the value only means how many aio
>operations can be outstanding at a given time. This just means that a
>single buffer will be submitted for read/write and a new one will not
>be submitted until that buffer's IO completes.
>
>  
>
>>3. For future reference, where can I find out what these Event error codes
>>mean to give me a glue of what's going wrong.
>>    
>>
>
>  The errors are errno values. I'll make a note to write up which errors
>are possible and what they are likely to mean.
>
>  
>
>>4. I sometimes see significant differences in the transfer speed reported on
>>the transmit and receiver ends. Is one more right than the other?
>>    
>>
>
>  Are the wall clock times for the data transfers small, on the order
>of a few seconds? How big of a wall clock time difference are you seeing?
>
>-Libor
>
>
>  
>