On Thu, Feb 09, 2006 at 04:16:54PM +0100, Eric Dumazet ([EMAIL PROTECTED]) wrote: > I had this idea after reading recent Van Jacobson paper about net channels. > > I'm surprised you see the benefit of net channels (which first assumption > is about the 50-100 ns cost of a memory cache miss) but keep this obvious > cache line ping pong in loopback driver.
Net channels are not about optimisations, but about completely new system. And resulted optimisations are just results of design, but not implementation. What about creating per-cpu jiffies variables, which could be read from such hot pathes, and it's values could be updated from some heavyweight functions like schedule()? > I did a benchmark test, using the volano benchmark > (http://www.volano.com/report/index.html) > > Platform : Dell PowerEdge 1600 SC with two Intel Xeon HT 2.0GHz cpu (total > of 4 logical cpus), FSB 533MHz, 2GB of ram. > > java version "1.5.0_06" > Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05) > Java HotSpot(TM) Server VM (build 1.5.0_06-b05, mixed mode) > > > Normal 2.6.16-rc2 (with dev->last_rx=jiffies in loopback driver) > > VolanoMark version = 2.5.0.9 > Messages sent = 20000 > Messages received = 380000 > Total messages = 400000 > Elapsed time = 27.239 seconds > Average throughput = 14685 messages per second > VolanoMark version = 2.5.0.9 > Messages sent = 20000 > Messages received = 380000 > Total messages = 400000 > Elapsed time = 24.871 seconds > Average throughput = 16083 messages per second > VolanoMark version = 2.5.0.9 > Messages sent = 20000 > Messages received = 380000 > Total messages = 400000 > Elapsed time = 28.698 seconds > Average throughput = 13938 messages per second > VolanoMark version = 2.5.0.9 > Messages sent = 20000 > Messages received = 380000 > Total messages = 400000 > Elapsed time = 24.302 seconds > Average throughput = 16460 messages per second > > total time = 108.956 > > > Patched 2.6.16-rc2 kernel (without dev->last_rx=jiffies; in loopback driver) > > VolanoMark version = 2.5.0.9 > Messages sent = 20000 > Messages received = 380000 > Total messages = 400000 > Elapsed time = 26.3 seconds > Average throughput = 15209 messages per second > VolanoMark version = 2.5.0.9 > Messages sent = 20000 > Messages received = 380000 > Total messages = 400000 > Elapsed time = 25.056 seconds > Average throughput = 15964 messages per second > VolanoMark version = 2.5.0.9 > Messages sent = 20000 > Messages received = 380000 > Total messages = 400000 > Elapsed time = 24.62 seconds > Average throughput = 16247 messages per second > VolanoMark version = 2.5.0.9 > Messages sent = 20000 > Messages received = 380000 > Total messages = 400000 > Elapsed time = 23.609 seconds > Average throughput = 16943 messages per second > > total time = 105.2 > > If I add the "dont refcount loopback netdevice" patch : > > VolanoMark version = 2.5.0.9 > Messages sent = 20000 > Messages received = 380000 > Total messages = 400000 > Elapsed time = 29.571 seconds > Average throughput = 13527 messages per second > VolanoMark version = 2.5.0.9 > Messages sent = 20000 > Messages received = 380000 > Total messages = 400000 > Elapsed time = 23.993 seconds > Average throughput = 16672 messages per second > VolanoMark version = 2.5.0.9 > Messages sent = 20000 > Messages received = 380000 > Total messages = 400000 > Elapsed time = 24.111 seconds > Average throughput = 16590 messages per second > VolanoMark version = 2.5.0.9 > Messages sent = 20000 > Messages received = 380000 > Total messages = 400000 > Elapsed time = 24.68 seconds > Average throughput = 16207 messages per second > > total = 102.355 > > Of course this is a benchmark, but normally used to test the OS capacity to > switch threads, not 'loopback performance' > > > - > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to [EMAIL PROTECTED] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Evgeniy Polyakov - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
