[ofa-general] Re: [PATCH 03/10] dev.c changes.

Krishna Kumar2 wrote:

Patrick McHardy [off-list ref] wrote on 07/20/2007 04:50:37 PM

quoted

Is there any downside in using batching with smaller queue sizes?
    

I think there is, but as yet I don't have any data (and 16 is probably
higher
than reqd) to show it. If the queue size is very small (like 4), the extra
processing to maintain this list may take more cycles than the performance
gains for sending out few skbs, esp since most xmits will send out 1 skb
and
skb batching takes places less often (when tx lock fails or queue gets
full).

OTOH, there might be a gain to even send out 2 skbs, the problem is in
doing
the extra processing before xmit and not at the time of xmit.

Does this sound OK ? If so, I will add the code to implement the TODO for
tx_queue_len checking too.
  

I can't really argue about the numbers, but it seems to me that only
devices which *usually* have a sufficient queue length will support
this, and anyone setting the queue length of a gbit device to <16 is
begging for trouble anyway. So it doesn't really seem worth to bloat
the code for handling an insane configuration as long as it doesn't
break.