I double checked. It does slightly improve the performance (in the order of a few thousand replies/sec). Larger MTUs decrease the CPU workload (by decreasing the number of transfers across the bus) and this means that more CPU cycles are available to the controller to process requests. However, I am not suggesting that people should use jumbo frames. Apparently running with more user-space threads does the trick here. Anyway, I should trust a profiler rather than guessing, so I will get back with a definite answer once I have done a more thorough evaluation.
Cheers, Amin On Wed, Dec 15, 2010 at 2:51 PM, kk yap <yap...@stanford.edu> wrote: > Random curiosity: Why would jumbo frames increases replies per sec? > > Regards > KK > > On 15 December 2010 11:45, Amin Tootoonchian <a...@cs.toronto.edu> wrote: >> I missed that. The single core throughput is ~250k replies/sec, two >> cores ~450k replies/sec, three cores ~650k replies/sec, four cores >> ~800 replies/sec. These numbers are higher than what I reported in my >> previous post. That is most probably because, right now, I am testing >> with MTU 9000 (jumbo frames) and with more user-space threads. >> >> Cheers, >> Amin >> >> On Wed, Dec 15, 2010 at 12:36 AM, Martin Casado <cas...@nicira.com> wrote: >>> Also, do you mind posting the single core throughput? >>> >>>> [cross-posting to nox-dev, openflow-discuss, ovs-discuss] >>>> >>>> I have prepared a patch based on NOX Zaku that improves its >>>> performance by a factor of>10. This implies that a single controller >>>> instance can run a large network with near a million flow initiations >>>> per second. I am writing to open up a discussion and get feedback from >>>> the community. >>>> >>>> Here are some preliminary results: >>>> >>>> - Benchmark configuration: >>>> * Benchmark: Throughput test of cbench (controller benchmarker) with >>>> 64 switches. Cbench is a part of the OFlops package >>>> (http://www.openflowswitch.org/wk/index.php/Oflops). Under throughput >>>> mode, cbench sends a batch of ofp_packet_in messages to the controller >>>> and counts the number of replies it gets back. >>>> * Benchmarker machine: HP ProLiant DL320 equipped with a 2.13GHz >>>> quad-core Intel Xeon processor (X3210), and 4GB RAM >>>> * Controller machine: Dell PowerEdge 1950 equipped with two 2.00GHz >>>> quad-core Intel Xeon processor (E5405), and 4GB RAM >>>> * Connectivity: 1Gbps >>>> >>>> - Benchmark results: >>>> * NOX Zaku: ~60k replies/sec (NOX Zaku only utilizes a single core). >>>> * Patched NOX: ~650k replies/sec (utilizing only 4 cores out of 8 >>>> available cores). The sustained controller->benchmarker throughput is >>>> ~400Mbps. >>>> >>>> The patch updates the asynchronous harness of NOX to a standard >>>> library (boost asynchronous I/O library) which simplifies the code >>>> base. It fixes the code in several areas, including but not limited >>>> to: >>>> >>>> - Multi-threading: The patch enables having any number of worker >>>> threads running on multiple cores. >>>> >>>> - Batching: Serving requests individually and sending replies one by >>>> one is quite inefficient. The patch tries to batch requests together >>>> were possible, as well replies (which reduces the number of system >>>> calls significantly). >>>> >>>> - Memory allocation: The standard C++ memory allocator is not robust >>>> in multi-threaded environments. Google's Thread-Caching Malloc >>>> (TCMalloc) or Hoard memory allocator perform much better for NOX. >>>> >>>> - Fully asynchronous operation: The patched version avoids wasting CPU >>>> cycles polling sockets, or event/timer dispatchers when not necessary. >>>> >>>> I would like to add that the patched version should perform much >>>> better than what I reported above (the number reported is with a run >>>> on 4 CPU cores). I guess a single NOX instance running on a machine >>>> with 8 CPU cores should handle well above 1 million flow initiation >>>> requests per second. Also having a more capable machine should help to >>>> serve more requests! The code will be made available soon and I will >>>> post updates as well. >>>> >>>> >>>> Cheers, >>>> Amin >>>> _______________________________________________ >>>> openflow-discuss mailing list >>>> openflow-disc...@lists.stanford.edu >>>> https://mailman.stanford.edu/mailman/listinfo/openflow-discuss >>> >>> >> >> _______________________________________________ >> nox-dev mailing list >> nox-dev@noxrepo.org >> http://noxrepo.org/mailman/listinfo/nox-dev_noxrepo.org >> > _______________________________________________ nox-dev mailing list nox-dev@noxrepo.org http://noxrepo.org/mailman/listinfo/nox-dev_noxrepo.org
