Messages in this thread |  | | Date | Sat, 20 Jan 2001 20:22:24 -0500 | From | Michael Lindner <> | Subject | Re: PROBLEM: select() on TCP socket sleeps for 1 tick even if data available |
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Chris Wedgwood wrote: > > On Sat, Jan 20, 2001 at 07:35:12PM -0500, Dan Maas wrote: > > Bingo! With this fix, 2.2.18 performance becomes almost identical to 2.4.0 > performance. I assume 2.4.0 disables Nagle by default on local > connections... > > 2.4.x has a smarter nagle algorithm.
Thanks again for all the help, guys...
Haven't installed 2.4 yet, but I tried the setsockoption route. Performance is better, but the two processes together never total more than 50% of the CPU (i.e. the thing is still schedule-bound, not compute bound, as it is on other platforms), and throughput is only up to 800 sends/sec. Better than the 100/sec. I was getting, but still a far cry from the identical box running Windows, where performance is 8K/sec.
...and I still don't understand why the identical program, but using one socket instead of 2 sockets, IS CPU bound, and gets on the order of 10K/sec. on the same HW. Diffs to produce 10K/sec. 1 socket version from my previous sample follow...
-- Mike Lindner
diff sockperf.c sockperf1.c 163c163 < if (pings++ < 1000) { --- > if (pings++ < 10000) { 177c177 < fprintf(stderr, "elapsed time for 1000 pingpongs is %g\n", now.tv_sec - then.tv_sec + (now.tv_usec - then.tv_usec) / 1000000.0); --- > fprintf(stderr, "elapsed time for 10000 pingpongs is %g\n", now.tv_sec - then.tv_sec + (now.tv_usec - then.tv_usec) / 1000000.0); 205c205 < int s = connectsock(argv[1], argv[3], "tcp"); --- > int s = r; 214c214 < int r = accept(f, (struct sockaddr *) &fsin, &alen); --- > int r = s; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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