problem about measurement-Collection of common programming errors
deadprogrammer
performance measurement
I am trying to quantify “site slowness”. In the olden days you just made sure that your HTML was lightweight, images optimized and servers not overloaded. In high end sites built on top of modern content management systems there are a lot more variables: third party advertising, trackers and various other callouts, the performance of CDN (interestingly enough sometimes content delivery networks make things worse), javascript execution, css overload, as well as all kinds of server side issues lik
PetPaulsen
measurement frequency-measurement
I want to measure the frequency (up to 300 Hz) of a rectangle signal, that varies between 0V and Vtop, where Vtop is anything between 5V and 15V. Because I cannot apply more than 5V to the microcontroller (PIC16F1827), I need to limit the voltage somehow.My first idea was to use a voltage divider. But then the 5V input signal would be to low.The second approach is using an opamp (TS914). When I am powering it at 5V, the output would not exceed 5V. I already have this opamp in my design, to filte
Hayden Thring
voltage measurement resistance
Below pictured is the basic circuit im working with, NCT is apparently pretty much a variable pot resistor.The measuring point ive added. According to the manual for my car, the sensor is provided with 5v by the ECU and it reads the return voltage.The Sensor decreases resistance with increasing temperature.However when I measure the voltage at illustrated point, I get lower voltage at higher temp, and higher voltage at lower temp, the inverse of what expected…What am I missing here about the b
Davy8
c# .net performance multithreading measurement
Right now we just use something like thisstopWatch.Start(); try{method();}finally{stopWatch.Stop();}Which works fine for synchronous methods, but some are executing asynchronously, so the time is skewed when multiple threads are executing. Is there an equivalent to System.Diagnostics.Stopwatch that will measure only time spend in the current thread?We want to collect data over an extended period of time in our internal beta(alpha?) release, and running under a profiler full time isn’
nairboon
performance computer-science performance-testing measurement perf
In parallel systems every process has an impact onto other processes, because they all compete for several scarce resources like cpu-caches, memory, disk I/O, network, etc.What method is best suited for measuring interference between processes? Such as Process A & B each access the disk heavily. So running them parallel will probably slower then running sequential (individual runtime). Because the bottleneck is the hard drive.If I don’t know exactly the behaviour of a process (disk-, memory-
portoalet
java time object measurement finalizer
From Effective Java 2nd Edition Item 7: Avoid Finalizers”Oh, and one more thing: there is a severe performance penalty for using finalizers. On my machine, the time to create and destroy a simple object is about 5.6 ns. Adding a finalizer increases the time to 2,400 ns. In other words, it is about 430 times slower to create and destroy objects with finalizers.”How can one measure the time to create and destroy an object? Do you just do:long start = System.nanoTime(); SimpleObject simpleObj = new
vis
haskell f# parallel-processing measurement
Assuming a single machine with 8 cores. In Haskell, you can compile using the threaded option, then during runtime use +RTS -Nx to specify the number of cores to be used. e.g.$ myprg args // sequential run $ myprg args +RTS -N1 // parallel run on 1..8 cores $ myprg args +RTS -N2 $ myprg args +RTS -N4 $ myprg args +RTS -N8From this, you get the runtimes using increasing number of cores, which you can then use to get speedups and plot a graph.How would you do this in F#, assuming I have a parallel
iceburn
java measurement memory-consumption
I’m currently using visualvm, but the problem I’m having is that I can’t save the graphs it generates. I need to report some data about its memory usage and running time, though running time is easy to get with System.nanoTime(). I’ve also tried the netbeans profiler but it isn’t what I want, since I’m not looking for specific parts that would be slowing it down or anything, so that would be overkill. The biggest problem with it is that it eats up too much processing time. Also doesn’t let me ca
Péter Török
c system infinite-loop measurement performance-measurement
I want to run an infinite loop for a while. Basically, i want to have something like this//do somethingwhile(1){//do some work }//do some other thingbut i want the running time of the loop to be fixed, example, the loop could be running for 5 seconds. Do somebody have an idea?
user11623
measurement
I’m in the process of setting up a test rig to automatically measure and test induced PCB voltages. The device I’m using (we’ll call it the meter) makes single ended measurements. The PCB output drives a 24V volt fan via two pins (which I assume are analogous to live / neutral) when not connected to the test rig. Firstly I’m confused over the concept of single ended measurements (I’ve been working in purely SW for several years now). If I wire the live and measure it relative to the meter’s inte
Chetan Bhargava
measurement photodiode phototransistor
I am designing a velocity measuring device and want to use 2 strings of 30 photo-transistors in series. The strings are 15mm apart and are illuminated by separate collimated light sources. The output of each string is a negative going pulse when any one or more of the photo-transistors in the string are blocked. This output goes to a comparator and then to a processor. I am having problems with the slow and varied rate of transition when different PDs are blocked. This is affecting the velocity
BSEE
adc measurement comparator
Here is revision 6 of the circuit. Hows it look? :)(This is an ohmmeter circuit. It measures resistances from 1 to 10M ohm with an accuracy of 1%. The resistor (not shown) is measured between J5 and J6. The comparator goes to the wakeup pin of a uC. The uC then wakes up and takes a reading using the SPI interface on the ADC. )
zebonaut
power-supply measurement inductor ferrite
I have large amounts of inductors and transformers from power supplies or other undocumented sources. They are of course completely unmarked and I have no idea what kind of ferrite material they are made of but sometimes I would like to use them in one-off power supplies or other experiments since ferrite cores are quite expensive to buy in low quantities.Do you know of any good methods to determine the important characteristics of the cores? \$A_L\$ is quite easy (I just wind \$N = 10\$ turns a
stevenvh
power temperature measurement analysis
I understand that this is arguably a peripheral electronics problem, but it seemed to fit here better than in physics.I’ve been doing some power electronics design work with large IGBTs mounted on forced-air aluminum heat sinks. To run thermal tests, we use USB thermocouple boxes and a spreadsheet to aggregate data. It takes 30-60 minutes for most of our heat sinks to reach thermal equilibrium. Given how often we run this kind of test, I decided it would be nice to add a feature to the spreadsh
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