[rds-devel] pull/review tcp fixes

[Andy Grover]

On 06/04/2010 02:48 PM, Zach Brown wrote:
> It looks like it was relatively simple to get the basic TCP transport
> functioning again.  The only real damage was calling the xmit path
> under a spinlock.  With that fixed it seems to work.
>
> The first two patches are trivial debugging fallout.

Looks good, thanks.

> The third patch is the meat of it.  If you could review it before
> pulling, that'd be super.  Removing c_send_generation makes sense to
> me, but maybe I'm missing something.

I've reviewed the code and it looks very good to me. I think this change 
will also keep iwarp transport working, heh. I'll test.

I think Chris's intention was that the atomic read of c_send_generation 
was less expensive than the spin_trylock_irqsave, so the 
released-from-send-duty thread could get out faster. After your patch it 
comes down to the cost of test_and_set_bit vs atomic_read..

Chris, do you recall what kind of performance impact the generation 
counter was having?

I've pulled these changes into devel and devel-against-mainline branches 
for now.

Thanks -- Regards -- Andy