From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <3570.145.249.13.3.1121167078.squirrel@mojo.myroom.ru> Date: Tue, 12 Jul 2005 15:17:58 +0400 (MSD) From: "Konstantin A. Lepikhov" To: sisyphus@altlinux.ru, devel-kernel@altlinux.ru User-Agent: SquirrelMail/1.4.5 [CVS] MIME-Version: 1.0 Content-Type: multipart/mixed;boundary="----=_20050712151758_25393" X-Priority: 3 (Normal) Importance: Normal X-AV-Checked: ClamAV using ClamSMTP Cc: Subject: [sisyphus] [Fwd: [ck] [ANNOUNCE] Interbench v0.20 - Interactivity benchmark] X-BeenThere: sisyphus@altlinux.ru X-Mailman-Version: 2.1.5 Precedence: list Reply-To: ALT Linux Sisyphus discussion list List-Id: ALT Linux Sisyphus discussion list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 Jul 2005 11:17:59 -0000 Archived-At: List-Archive: ------=_20050712151758_25393 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit ------------------ Исходное сообщение ------------------- Тема: [ck] [ANNOUNCE] Interbench v0.20 - Interactivity benchmark От: "Con Kolivas" Дата: Втр, Июль 12, 2005 15:10 Кому: "linux kernel mailing list" Копия: "ck list" -------------------------------------------------------------------------- Interbench - The Linux Interactivity Benchmark v0.20 http://interbench.kolivas.org direct download link: http://ck.kolivas.org/apps/interbench/interbench-0.20.tar.bz2 Introduction This benchmark application is designed to benchmark interactivity in Linux. Interactivity, what is it? There has been a lot of talk about what makes up a nice feeling desktop under linux. It comes down to two different but intimately related parameters which are not well defined. We often use the terms responsiveness and interactivity in the same sentence, but I'd like to separate the two. As there is no formal definition I prefer to define them as such: Responsiveness: The rate at which your workloads can proceed under different load conditions. Interactivity: The scheduling latency and jitter present in tasks where the user would notice a palpable deterioration under different load conditions. Responsiveness would allow you to continue using your machine without too much interruption to your work, whereas interactivity would allow you to play audio or video without any dropouts, or drag a gui window across the screen and have it render smoothly across the screen without jerks . Contest was a benchmark originally written by me to test system responsiveness, and interbench is a benchmark I wrote as a sequel to contest to test interactivity. It is designed to measure the effect of changes in Linux kernel design or system configuration changes such as cpu, I/O scheduler and filesystem changes and options. With careful benchmarking, different hardware can be compared. What does it do? It is designed to emulate the cpu scheduling behaviour of interactive tasks and measure their scheduling latency and jitter. It does this with the tasks on their own and then in the presence of various background loads, both with configurable nice levels and the benchmarked tasks can be real time. How does it work? First it benchmarks how best to reproduce a fixed percentage of cpu usage on the machine currently being used for the benchmark. It saves this to a file and then uses this for all subsequent runs to keep the emulation of cpu usage constant. It runs a real time high priority timing thread that wakes up the thread or threads of the simulated interactive tasks and then measures the latency in the time taken to schedule. As there is no accurate timer driven scheduling in linux the timing thread sleeps as accurately as linux kernel supports, and latency is considered as the time from this sleep till the simulated task gets scheduled. What interactive tasks are simulated and how? X: X is simulated as a thread that uses a variable amount of cpu ranging from 0 to 100%. This simulates an idle gui where a window is grabbed and then dragged across the screen. Audio: Audio is simulated as a thread that tries to run at 50ms intervals that then requires 5% cpu. This behaviour ignores any caching that would normally be done by well designed audio applications, but has been seen as the interval used to write to audio cards by a popular linux audio player. It also ignores any of the effects of different audio drivers and audio cards. Audio can also be run as a real time SCHED_FIFO task. Video: Video is simulated as a thread that tries to receive cpu 60 times per second and uses 40% cpu. This would be quite a demanding video playback at 60fps. Like the audio simulator it ignores caching, drivers and video cards. As per audio, video can be run SCHED_FIFO. What loads are simulated? None: Otherwise idle system. Video: The video simulation thread is also used as a background load. X: The X simulation thread is used as a load. Burn: A configurable number of threads fully cpu bound (4 by default). Write: A streaming write to disk repeatedly of a file the size of physical ram. Read: Repeatedly reading a file from disk the size of physical ram (to avoid any caching effects). Compile: Simulating a heavy 'make -j4' compilation by running Burn, Write and Read concurrently. Memload: Simulating heavy memory and swap pressure by repeatedly accessing 110% of available ram and moving it around and freeing it. What is measured and what does it mean? 1. The average scheduling latency (time to requesting cpu till actually getting it) of deadlines met during the test period. 2. The scheduling jitter is represented by calculating the standard deviation of the latency 3. The maximum latency seen during the test period 4. Percentage of desired cpu 5. Percentage of deadlines met. This data is output to console and saved to a file which is stamped with the kernel name and date. Use fixed font for clarity: Sample: --- Benchmarking X in the presence of loads --- Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.495 +/- 0.495 45 100 96 Video 11.7 +/- 11.7 1815 89.6 62.7 Burn 27.9 +/- 28.1 3335 78.5 44 Write 4.02 +/- 4.03 372 97 78.7 Read 1.09 +/- 1.09 158 99.7 88 Compile 28.8 +/- 28.8 3351 78.2 43.7 Memload 2.81 +/- 2.81 187 98.7 85 What can be seen here is that never during this test run were all the so called deadlines met by the X simulator, although all the desired cpu was achieved under no load. In X terms this means that every bit of window movement was drawn while moving the window, but some were delayed and there was enough time to catch up before the next deadline. In the 'Burn' column we can see that only 44% of the deadlines were met, and only 78.5% of the desired cpu was achieved. This means that some deadlines were so late (%deadlines met was low) that some redraws were dropped entirely to catch up. In X terms this would translate into jerky movement, in audio it would be a skip, and in video it would be a dropped frame. Note that despite the massive maximum latency of >3seconds, the average latency is still less than 30ms. This is because redraws are dropped in order to catch up usually by these sorts of applications. What is relevant in the data? The results pessimise quite a lot what happens in real world terms because they ignore the reality of buffering, but this allows us to pick up subtle differences more readily. In terms of what would be noticed by the end user, dropping deadlines would make noticable clicks in audio, subtle visible frame time delays in video, and loss of "smooth" movement in X. Dropping desired cpu would be much more noticeable with audio skips, missed video frames or jerks in window movement under X. The magnitude of these would be best represented by the maximum latency. When the deadlines are actually met, the average latency represents how "smooth" it would look. Average humans' limit of perception for jitter is in the order of 7ms. Trained audio observers might notice much less. How to use it? In response to critisicm of difficulty in setting up my previous benchmark, contest, I've made this as simple as possible. Short version: make ./interbench Longer version: Build with 'make'. It is a single executable once built so if you desire to install it simply copy the interbench binary wherever you like. To get good reproducible data from it you should boot into runlevel one so that nothing else is running on the machine. All power saving (cpu throttling, cpu frequency modifications) must be disabled on the first run to get an accurate measurement for cpu usage. You may enable them later if you are benchmarking their effect on interactivity on that machine. Root is almost mandatory for this benchmark, or real time privileges at the very least. You need free disk space in the directory it is being run in the order of 2* your physical ram for the disk loads. A default run in v0.20 takes about 15 minutes to complete, longer if your disk is slow. Command line options supported: interbench [-l ] [-L ] [-t ] [-N ] [-b] [-c] [-h] [-n] [-r] -l Use loops per sec (default: use saved benchmark) -L Use cpu load of with burn load (default: 4) -t Seconds to run each benchmark (default: 30) -B Nice the benchmarked thread to (default: 0) -N Nice the load thread to (default: 0) -b Benchmark loops_per_ms even if it is already known -c Output to console only (default: use console and logfile) -r Perform real time scheduling benchmarks (default: non-rt) -h Show this help There is one hidden option which is not supported by default, -u which emulates a uniprocessor when run on an smp machine. The support for cpu affinity is not built in by default because there are multiple versions of the sched_setaffinity call in glibc that not only accept different variable types but across architectures take different numbers of arguments. For x86 support you can change the '#if 0' in interbench.c to '#if 1' to enable the affinity support to be built in. The function on x86_64 for those very keen does not have the sizeof argument. So how does -ck perform? As much as I'd like to say it was a walkover I have to admit you need to squint hard to be convinced that -ck is better overall. Both mainline and -ck perform better in different load settings: The SCHED_NORMAL nice 0 runs are as below, performed on a pentium M 1.7Ghz: Benchmarking kernel 2.6.13-rc1 with datestamp 200507121411 --- Benchmarking Audio in the presence of loads --- Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.003 +/- 0 0.005 100 100 Video 1.02 +/- 0.487 1.68 100 100 X 1.32 +/- 2.22 10 100 100 Burn 0.518 +/- 306004 52 100 99 Write 0.031 +/- 0.209 2.58 100 100 Read 0.006 +/- 0.00173 0.01 100 100 Compile 4.59 +/- 5.74 426 96.5 94 Memload 0.021 +/- 0.0697 0.659 100 100 --- Benchmarking Video in the presence of loads --- Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.003 +/- 0 0.005 100 100 X 3.27 +/- 3.2 41.3 88.8 77.7 Burn 0.003 +/- 0.001 0.005 100 100 Write 0.151 +/- 0.67 50 99.5 99 Read 0.004 +/- 0.00173 0.037 100 100 Compile 0.025 +/- 0.248 4.81 100 100 Memload 0.018 +/- 0.0572 0.715 100 100 --- Benchmarking X in the presence of loads --- Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.009 +/- 0.0966 1 100 99 Video 4.46 +/- 4.43 572 91.9 66 Burn 1.58 +/- 1.58 156 100 98 Write 0.002 +/- 0.0237 4 100 98 Read 0.008 +/- 0.0797 15 100 96 Compile 0.009 +/- 0.0896 2 100 99 Memload 0.108 +/- 0.13 10 100 98 Benchmarking kernel 2.6.12-rc6-ck1 with datestamp 200507121345 --- Benchmarking Audio in the presence of loads --- Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.003 +/- 0 0.005 100 100 Video 0.003 +/- 0 0.004 100 100 X 2.53 +/- 3.01 11 100 100 Burn 0.294 +/- 1.47 11 100 100 Write 0.025 +/- 0.116 1.02 100 100 Read 0.007 +/- 0.001 0.01 100 100 Compile 0.393 +/- 1.68 11 100 100 Memload 0.095 +/- 0.545 6 100 100 --- Benchmarking Video in the presence of loads --- Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.003 +/- 0.00245 0.052 100 100 X 3.57 +/- 3.21 22.7 95.7 91.3 Burn 0.837 +/- 2.49 50 97.7 95.5 Write 0.094 +/- 0.596 16.7 100 99.8 Read 0.005 +/- 0.00872 0.169 100 100 Compile 0.543 +/- 1.91 33.3 98.8 97.7 Memload 0.21 +/- 0.836 16.7 99.7 99.3 --- Benchmarking X in the presence of loads --- Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met None 0.009 +/- 0.0964 1 100 99 Video 2.31 +/- 2.27 754 90.9 65 Burn 0.129 +/- 0.151 12 100 98 Write 0.069 +/- 0.112 6 100 98 Read 0.009 +/- 0.0896 1 100 99 Compile 0.039 +/- 0.102 3 100 98 Memload 0.004 +/- 0.0408 1 100 99 The full logs are available here (including niced runs and real time runs): http://ck.kolivas.org/apps/interbench/2.6.13-rc1.log http://ck.kolivas.org/apps/interbench/2.6.12-rc6-ck1.log Thanks: For help from Zwane Mwaikambo, Bert Hubert, Seth Arnold, Rik Van Riel, Nicholas Miell and John Levon. Aggelos Economopoulos for contest code, and Bob Matthews for irman (mem_load) code. This was quite some time in the making... I realise there's so much more that could be done trying to simulate the interactive tasks and the loads, but this is a start, it's quite standardised and the results are reproducible. Adding more code to simulate loads and threads to benchmark is quite easy if someone wishes to suggest or code up something I'm all ears. Of course bugfixes, comments and suggestions are most welcome. Cheers, Con Kolivas _______________________________________________ ck@ ck mailing list. Please reply-to-all when posting. If replying to an email please reply below the original message. http://bhhdoa.org.au/mailman/listinfo/ck -- WBR et al. ------=_20050712151758_25393 Content-Type: application/pgp-signature; name="untitled-1.2" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="untitled-1.2" LS0tLS1CRUdJTiBQR1AgU0lHTkFUVVJFLS0tLS0KVmVyc2lvbjogR251UEcgdjEuNC4xIChHTlUv TGludXgpCgppRDhEQlFCQzA2VXpaVWc3K3RwNm1SVVJBajdrQUo5VzhuT0ovL05pZE5XKzVKYTJB UjhIRGV5QVFBQ2VQWWk4CjE3NkZMSUd1azEzMGtGM0VpNm4yTk1VPQo9b3NGegotLS0tLUVORCBQ R1AgU0lHTkFUVVJFLS0tLS0K ------=_20050712151758_25393--