Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261511AbUKWSxN (ORCPT ); Tue, 23 Nov 2004 13:53:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261431AbUKWR7f (ORCPT ); Tue, 23 Nov 2004 12:59:35 -0500 Received: from mail3.utc.com ([192.249.46.192]:45728 "EHLO mail3.utc.com") by vger.kernel.org with ESMTP id S261356AbUKWRx0 (ORCPT ); Tue, 23 Nov 2004 12:53:26 -0500 Message-ID: <41A37901.8050702@cybsft.com> Date: Tue, 23 Nov 2004 11:53:05 -0600 From: "K.R. Foley" Organization: Cybersoft Solutions, Inc. User-Agent: Mozilla Thunderbird 0.9 (X11/20041103) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Ingo Molnar CC: linux-kernel@vger.kernel.org, Lee Revell , Rui Nuno Capela , Mark_H_Johnson@Raytheon.com, Bill Huey , Adam Heath , Florian Schmidt , Thomas Gleixner , Michal Schmidt , Fernando Pablo Lopez-Lezcano , Karsten Wiese , Gunther Persoons , emann@mrv.com, Shane Shrybman , Amit Shah , Esben Nielsen Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm2-V0.7.30-9 References: <20041109160544.GA28242@elte.hu> <20041111144414.GA8881@elte.hu> <20041111215122.GA5885@elte.hu> <20041116125402.GA9258@elte.hu> <20041116130946.GA11053@elte.hu> <20041116134027.GA13360@elte.hu> <20041117124234.GA25956@elte.hu> <20041118123521.GA29091@elte.hu> <20041118164612.GA17040@elte.hu> <20041122005411.GA19363@elte.hu> <20041123175823.GA8803@elte.hu> In-Reply-To: <20041123175823.GA8803@elte.hu> X-Enigmail-Version: 0.86.1.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: multipart/mixed; boundary="------------000904080809060807010003" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6670 Lines: 319 This is a multi-part message in MIME format. --------------000904080809060807010003 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Ingo Molnar wrote: > i have released the -V0.7.30-9 Real-Time Preemption patch, which can be > downloaded from the usual place: > A couple of observations that I would like to share: 1) With all of the tracing compiled in, there is a measurable amount of additional latency, even when the tracing is disabled via the proc interfaces. So if you want to measure best-case (or worst-case) latencies turn off the tracing facilities to do so. For example, using a blocking read, the worst case latency from interrupt to read: wo/tracing ~68 usec, w/tracing ~110 usec. I am attaching two histograms generated by the rtc histogram by running a slightly modified version of realfeel. 2) Also there is a big difference in latencies between blocking reads and using signals to notify the process that data is available. I am also attaching a histogram generated by the rtc histogram by running amlat. Part of the numbers in the > 10 msec bucket are into the hundreds of msecs. All of these numbers were generated using a comparable load from stress-kernel. kr --------------000904080809060807010003 Content-Type: text/plain; name="notraceread.txt" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="notraceread.txt" No tracing using read: rtc latency histogram of {realfeel/5162, 671921 samples}: 3 221135 4 32396 5 38047 6 62650 7 99079 8 62347 9 47702 10 37572 11 27323 12 16734 13 9889 14 6081 15 3607 16 2214 17 1440 18 784 19 494 20 355 21 269 22 215 23 186 24 163 25 124 26 123 27 93 28 85 29 85 30 90 31 80 32 61 33 72 34 47 35 53 36 49 37 39 38 29 39 26 40 22 41 15 42 19 43 18 44 23 45 15 46 12 47 4 48 10 49 12 50 4 51 4 52 4 53 3 54 2 55 4 56 3 57 2 59 1 60 1 61 1 62 1 67 1 68 2 --------------000904080809060807010003 Content-Type: text/plain; name="traceon.txt" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="traceon.txt" Tracing on using read: Nov 22 19:37:39 porky kernel: rtc latency histogram of {realfeel/6592, 487037 samples}: Nov 22 19:37:39 porky kernel: 13 10 Nov 22 19:37:39 porky kernel: 14 88142 Nov 22 19:37:39 porky kernel: 15 113256 Nov 22 19:37:39 porky kernel: 16 77884 Nov 22 19:37:39 porky kernel: 17 60492 Nov 22 19:37:39 porky kernel: 18 41451 Nov 22 19:37:39 porky kernel: 19 23587 Nov 22 19:37:39 porky kernel: 20 15409 Nov 22 19:37:39 porky kernel: 21 11975 Nov 22 19:37:39 porky kernel: 22 14672 Nov 22 19:37:39 porky kernel: 23 11843 Nov 22 19:37:39 porky kernel: 24 8318 Nov 22 19:37:39 porky kernel: 25 5595 Nov 22 19:37:39 porky kernel: 26 3546 Nov 22 19:37:39 porky kernel: 27 2057 Nov 22 19:37:39 porky kernel: 28 1192 Nov 22 19:37:39 porky kernel: 29 819 Nov 22 19:37:39 porky kernel: 30 682 Nov 22 19:37:39 porky kernel: 31 665 Nov 22 19:37:39 porky kernel: 32 662 Nov 22 19:37:39 porky kernel: 33 540 Nov 22 19:37:39 porky kernel: 34 494 Nov 22 19:37:39 porky kernel: 35 433 Nov 22 19:37:39 porky kernel: 36 290 Nov 22 19:37:39 porky kernel: 37 227 Nov 22 19:37:39 porky kernel: 38 189 Nov 22 19:37:39 porky kernel: 39 129 Nov 22 19:37:39 porky kernel: 40 110 Nov 22 19:37:39 porky kernel: 41 78 Nov 22 19:37:39 porky kernel: 42 85 Nov 22 19:37:39 porky kernel: 43 102 Nov 22 19:37:39 porky kernel: 44 314 Nov 22 19:37:39 porky kernel: 45 189 Nov 22 19:37:39 porky kernel: 46 137 Nov 22 19:37:39 porky kernel: 47 105 Nov 22 19:37:39 porky kernel: 48 147 Nov 22 19:37:39 porky kernel: 49 101 Nov 22 19:37:39 porky kernel: 50 99 Nov 22 19:37:39 porky kernel: 51 93 Nov 22 19:37:39 porky kernel: 52 61 Nov 22 19:37:39 porky kernel: 53 57 Nov 22 19:37:39 porky kernel: 54 44 Nov 22 19:37:39 porky kernel: 55 50 Nov 22 19:37:39 porky kernel: 56 49 Nov 22 19:37:39 porky kernel: 57 50 Nov 22 19:37:39 porky kernel: 58 48 Nov 22 19:37:39 porky kernel: 59 49 Nov 22 19:37:39 porky kernel: 60 41 Nov 22 19:37:39 porky kernel: 61 31 Nov 22 19:37:39 porky kernel: 62 23 Nov 22 19:37:39 porky kernel: 63 19 Nov 22 19:37:39 porky kernel: 64 23 Nov 22 19:37:39 porky kernel: 65 27 Nov 22 19:37:39 porky kernel: 66 18 Nov 22 19:37:39 porky kernel: 67 17 Nov 22 19:37:39 porky kernel: 68 15 Nov 22 19:37:39 porky kernel: 69 16 Nov 22 19:37:39 porky kernel: 70 17 Nov 22 19:37:39 porky kernel: 71 11 Nov 22 19:37:39 porky kernel: 72 11 Nov 22 19:37:39 porky kernel: 73 19 Nov 22 19:37:40 porky kernel: 74 15 Nov 22 19:37:40 porky kernel: 75 24 Nov 22 19:37:40 porky kernel: 76 26 Nov 22 19:37:40 porky kernel: 77 14 Nov 22 19:37:40 porky kernel: 78 15 Nov 22 19:37:40 porky kernel: 79 17 Nov 22 19:37:40 porky kernel: 80 19 Nov 22 19:37:40 porky kernel: 81 12 Nov 22 19:37:40 porky kernel: 82 4 Nov 22 19:37:40 porky kernel: 83 7 Nov 22 19:37:40 porky kernel: 84 9 Nov 22 19:37:40 porky kernel: 85 8 Nov 22 19:37:40 porky kernel: 86 11 Nov 22 19:37:40 porky kernel: 87 8 Nov 22 19:37:40 porky kernel: 88 4 Nov 22 19:37:40 porky kernel: 89 3 Nov 22 19:37:40 porky kernel: 90 1 Nov 22 19:37:40 porky kernel: 91 5 Nov 22 19:37:40 porky kernel: 92 5 Nov 22 19:37:40 porky kernel: 94 3 Nov 22 19:37:40 porky kernel: 95 1 Nov 22 19:37:40 porky kernel: 96 2 Nov 22 19:37:40 porky kernel: 97 2 Nov 22 19:37:40 porky kernel: 98 2 Nov 22 19:37:40 porky kernel: 99 1 Nov 22 19:37:40 porky kernel: 101 1 Nov 22 19:37:40 porky kernel: 107 2 Nov 22 19:37:40 porky kernel: 110 1 --------------000904080809060807010003 Content-Type: text/plain; name="notracesig.txt" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="notracesig.txt" No tracing using signals: rtc latency histogram of {amlat/7215, 535020 samples}: 4 1 9 18916 10 125448 11 29422 12 41496 13 22222 14 15344 15 12256 16 10935 17 11157 18 11192 19 11456 20 12994 21 13832 22 14704 23 14330 24 12625 25 11837 26 11839 27 11206 28 10307 29 10057 30 10183 31 13115 32 11438 33 11897 34 11559 35 7817 36 5823 37 4660 38 3944 39 3106 40 2763 41 2424 42 1961 43 1729 44 1348 45 1154 46 984 47 801 48 682 49 537 50 467 51 345 52 288 53 214 54 182 55 162 56 131 57 117 58 135 59 118 60 111 61 120 62 118 63 89 64 103 65 95 66 92 67 85 68 62 69 45 70 61 71 39 72 29 73 40 74 28 75 25 76 25 77 18 78 18 79 11 80 13 81 9 82 13 83 10 84 11 85 5 86 2 87 4 88 2 89 3 90 2 91 5 92 2 93 1 94 2 95 4 96 3 97 2 98 1 99 3 103 1 104 1 108 2 118 1 7860 1 9999 43 --------------000904080809060807010003-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/