These are patches designed to improve system responsiveness and interactivity. It is configurable to any workload but the default ck patch is aimed at the desktop and cks is available with more emphasis on serverspace. Apply to 2.6.14 http://ck.kolivas.org/patches/2.6/2.6.14/2.6.14-ck4/patch-2.6.14-ck4.bz2 or server version http://ck.kolivas.org/patches/cks/patch-2.6.14-cks4.bz2 web: http://kernel.kolivas.org all patches: http://ck.kolivas.org/patches/ Split patches available. Changes: Added: +patch-2.6.14.1 Latest stable patch +net-fix_zero-size_datagram_reception.patch Bugfix queued for 2.6.14.2 +sched-staircase12.2_13.patch Major update in the staircase code. This now makes the interactive mode work out a simple mathematical calculation to determine the cpu percentage of entitled cpu a task uses and use that to determine what best dynamic priority (and thus how low the latency is). This means that a low cpu using task can have very low latency even in the presence of much less niced tasks. For example a nice 0 task in the presence of a nice -20 task can still have low latency if it uses very little cpu. This means that 'nice' is a determinant of cpu entitlement, but no longer the prime determinant of latency. It is thus possible to even run low cpu using audio apps at nice 19. Running audio at nice 19 would be unusual, though. However this does help for the opposite as well - there are kernel threads that run nice 0, -5 and even -20, when normal user tasks run at nice 0. Some of these kernel threads and workqueues can use extraordinary amounts of cpu as well. These are real world examples where it would help on normal desktops now. Interbench benchmarks demonstrate this below. -2614ck3-version.diff +2614ck4-version.diff Version update --- If you are new to interbench results, the order of importance is from right to left, where deadlines met and desired cpu should be as close to 100% as possible, amd max latency and average latency as low as possible. Asterisks have been placed to the right to indicate where one kernel outperforms the other. Use a fixed font to be able to read this table! Interbench 0.29 results on 3Ghz P4 uniprocessor: Here is mainline 2.6.14, with the benchmarked interactive process running at nice 19: --- Benchmarking simulated cpu of Audio nice 19 in the presence of simulated Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.004 +/- 0.00442 0.008 100 100 Video 0.004 +/- 0.00491 0.009 100 100 X 36.4 +/- 62.7 233 96 63.8 Burn 673 +/- 699 701 0.568 0.568 Write 1.39 +/- 9.22 118 99.5 99.5 Read 0.01 +/- 0.0133 0.105 100 100 Compile 774 +/- 803 1003 0.559 0 Memload 4.78 +/- 27.9 225 95.5 95.5 --- Benchmarking simulated cpu of Video nice 19 in the presence of simulated Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.004 +/- 0.00493 0.026 100 100 * X 21.9 +/- 50 266 54.2 48.8 Burn 741 +/- 770 771 0.174 0.174 Write 2.58 +/- 11.2 140 96.1 90.1 Read 0.009 +/- 0.0176 0.182 100 100 Compile 758 +/- 783 877 0.173 0 Memload 2.38 +/- 20.3 269 93.9 92.9 --- Benchmarking simulated cpu of X nice 19 in the presence of simulated --- Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.009 +/- 0.1 1 100 99 * Video 13 +/- 23.7 60 69.8 53 Burn 607 +/- 634 750 1.15 1.15 Write 6.48 +/- 17.4 90 80.5 66.7 Read 0.227 +/- 1.05 6 92.7 89.6 Compile 680 +/- 720 957 1.14 1.14 Memload 7.84 +/- 31.7 272 76.6 66.4 Note the massive dropped deadlines even with something using just 5% cpu when run at nice 19 Here is 2.6.14-ck4 running staircase v13: --- Benchmarking simulated cpu of Audio nice 19 in the presence of simulated Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.004 +/- 0.00419 0.009 100 100 Video 0.004 +/- 0.00457 0.008 100 100 X 0.054 +/- 0.388 4 100 100 * Burn 3.27 +/- 18.8 136 98 97.4 * Write 1.3 +/- 11.7 120 99 99 * Read 0.011 +/- 0.0119 0.056 100 100 Compile 2.81 +/- 16.6 126 98 98 * Memload 3.39 +/- 22 206 97.5 97.5 * --- Benchmarking simulated cpu of Video nice 19 in the presence of simulated Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.031 +/- 0.682 16.7 100 99.8 X 9.87 +/- 25.5 133 74.8 67.4 * Burn 6.33 +/- 31.7 483 85.8 79.6 * Write 1.69 +/- 11.7 172 97.1 94.6 * Read 0.011 +/- 0.0142 0.107 100 100 Compile 7.17 +/- 46.4 617 78.3 75.7 * Memload 2.46 +/- 20.8 245 92.9 92.9 --- Benchmarking simulated cpu of X nice 19 in the presence of simulated --- Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.237 +/- 2.3 23 100 98 Video 13 +/- 23.6 60 69.8 53 Burn 327 +/- 659 1398 20.5 16.4 * Write 2.9 +/- 13.4 108 73.3 69.9 * Read 0.217 +/- 1.01 6 92.7 89.6 Compile 365 +/- 691 1519 19.3 14.3 * Memload 8.42 +/- 19.8 92 80.8 73.2 * You can see here that the audio benchmark meets more than 97% of the deadlines even in extreme loads when run at nice 19, and interbench ignores the effect of buffering. With some buffering it is unlikely to skip sound even at nice 19. Now if you move on to video and then X you can see that the improvement over mainline gets progressively less as each load uses more cpu. This is because the latency is determined by cpu% of entitlement. Even so, the deadlines met are significantly higher (especially for video which doesnt drop below 67% compared to mainline which bottoms out at 1%). --- Moving on to the more "real world" example of nice 0 interactive task in the presence of background loads running at nice -5: Mainline 2.6.14: --- Benchmarking simulated cpu of Audio in the presence of simulated nice -5 Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.004 +/- 0.00526 0.029 100 100 Video 0.004 +/- 0.00484 0.007 100 100 X 36 +/- 59.8 113 75.5 63.3 Burn 6.78 +/- 90.5 1200 88.1 88 Write 2.21 +/- 13.5 141 99 99 Read 0.01 +/- 0.0146 0.111 100 100 Compile 22.1 +/- 183 1600 69.7 69.3 Memload 0.191 +/- 0.957 7.07 100 100 --- Benchmarking simulated cpu of Video in the presence of simulated nice -5 Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.004 +/- 0.00415 0.01 100 100 * X 21.4 +/- 51.1 417 53.7 48.2 Burn 23.6 +/- 186 1467 41.4 41 Write 3.11 +/- 16.9 315 93.7 88.8 Read 0.009 +/- 0.0145 0.12 100 100 Compile 21.5 +/- 171 1400 43.7 43.1 Memload 0.292 +/- 2.08 28.3 100 99 --- Benchmarking simulated cpu of X in the presence of simulated nice -5 --- Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.009 +/- 0.0995 1 100 99 Video 13 +/- 23.7 60 69.8 53 * Burn 77.5 +/- 306 1404 45.6 43.8 Write 9.71 +/- 28.4 224 76.2 64.9 Read 0.245 +/- 1.13 6 91.1 88.9 Compile 97.6 +/- 365 1564 41.1 39.2 Memload 4.31 +/- 12.7 72 57.6 51.2 You can see that without any buffering, it is possible even at nice 0 for audio to miss almost 40% of the deadlines under a nice -5 X load (or equivalent load from kernel threads etc). And here is 2.6.14-ck4: --- Benchmarking simulated cpu of Audio in the presence of simulated nice -5 Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.003 +/- 0.00351 0.009 100 100 Video 0.004 +/- 0.00451 0.009 100 100 X 0.287 +/- 1.43 10 100 100 * Burn 0.004 +/- 0.00457 0.008 100 100 * Write 0.009 +/- 0.0102 0.018 100 100 * Read 0.011 +/- 0.0128 0.069 100 100 Compile 0.009 +/- 0.0107 0.039 100 100 * Memload 0.037 +/- 0.167 2 100 100 --- Benchmarking simulated cpu of Video in the presence of simulated nice -5 Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.031 +/- 0.682 16.7 100 99.8 X 3.43 +/- 8.46 27.7 100 83 * Burn 0.032 +/- 0.681 16.7 100 99.8 * Write 0.006 +/- 0.00846 0.07 100 100 * Read 0.011 +/- 0.0115 0.04 100 100 Compile 0.04 +/- 0.683 16.7 100 99.8 * Memload 0.062 +/- 0.694 16.7 100 99.8 * --- Benchmarking simulated cpu of X in the presence of simulated nice -5 --- Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.009 +/- 0.0995 1 100 99 Video 13.5 +/- 24.1 60 67.7 50.8 Burn 0.117 +/- 0.783 6 98.1 96.1 * Write 0.147 +/- 0.751 4 94.4 92.4 * Read 0.009 +/- 0.0995 1 100 99 * Compile 0.147 +/- 0.751 4 94.4 92.4 * Memload 0.176 +/- 1.69 17 100 99 * Whereas here audio does not drop a single deadline even without any buffering. Video and even X also show significant improvement. Cheers, Con
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