Hi again, On Fri, Sep 17, 2010 at 3:11 PM, Lars Ellenberg <[email protected]>wrote:
> On Fri, Sep 17, 2010 at 02:12:35PM -0500, J. Ryan Earl wrote: > > Is this the fix to which you refer? > > http://www.mail-archive.com/[email protected]/msg10615.html > > That's certainly relevant as well, > but it would have returned EAFNOSUPPORT, which is 97. > I'm going through the code and that patch is already included anyway. > > > I doubt that this has anything to do with performance, btw, > it is just the address lookup during connect. > Oh, that blows then. > > My guess is if you strace a netcat in userland, using your sdp preload > thingy, you'll likely see that it only creates the socket as > AF_INET_SDP, but all the rest of the network functions keep using > AF_INET, so no-one ever noticed. If that is intentional, we'd have to > adjust that in DRBD. If not, it needs to be fixed in the sdp stack. > It seems to intercept AF_INET. The LD_PRELOAD doesn't change the strace except for opening the shared object. > > DRBD over SDP performance tuning is a bit tricky, > and no, I don't remember the details, it's been a while. > > I think cpu usage dropped considerable, thats a plus. But neither > single write latency nor sequential throughput of a single connection > improved much or even degraded respective to IPoIB. If you have > multiple DRBD, thus multiple connections, the cumulative throughput > scaled better, though. > Actually CPU usage went up. The wall time was 50% longer with 10% more CPU time. > > But please go ahead and tune your stack, on your hardware, which may be > more capable than the test lab hardware we used. > Depending on your hardware, and the quality recommendations of > your SDP tuning expert, your findings may be different. > I'm not sure how to tune SDP, but I'll look into it. ssocks when I tried didn't seem to need tuning. With 2 ports, I was getting better performance than with IB and SDP, though it had other issues. Thanks! -JR
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