As per you test case and duration settings, I think, you are making confusion with the Threads and Requests. In short: You must use Ramp-up as 240 seconds for this scenario. Let me describe you in details: Ramp up is the time in which all the users arrive on your tested application server. Requests are … Read more
The one flaw in that approach is that the “real” time doSomething() takes to execute can vary wildly depending on what other programs are running on the system and what its load is. This makes the performance measurement somewhat imprecise. One more accurate way of tracking the time it takes to execute code, assuming the … Read more
The following tests (compiled in Release mode, executed on a Mac Pro) indicate that filteredArrayUsingPredicate is slower than indexesOfObjectsPassingTest if you use a “textual” predicate, but faster if you use block-based predicate. The fasted method in my test was a simple (fast-enumeration) loop that adds all matching objects to a mutable array. Results for filtering … Read more
Merge sort does fewer compares, but more moves than quick sort. Having to call a function to do the compares increases the overhead for compares, which makes quick sort slower. All those if statements in the example quick sort is also slowing it down. If the compare and swap are done inline, then quick sort … Read more
One of the Roslyn engineers who specializes in understanding optimization of stack usage took a look at this and reports to me that there seems to be a problem in the interaction between the way the C# compiler generates local variable stores and the way the JIT compiler does register scheduling in the corresponding x86 … Read more
tl;dr doNotOptimizeAway creates an artificial “use”s. A little bit of terminology here: a “def” (“definition”) is a statement, which assigns a value to a variable; a “use” is a statement, which uses the value of a variable to perform some operation. If from the point immediately after a def, all the paths to the program … Read more
UPDATE 8/1730/2020: TF 2.3 has finally done it: all cases run as fast, or notably faster, than any previous version. Further, my previous update was unfair to TF; my GPU was to blame, has been overheating lately. If you see a rising stem plot of iteration times, it’s a reliable symptom. Lastly, see a dev’s … Read more
Stricto sensu, the GCC compiler middle-end is made of a sequence (actually a nested tree, dynamically changing during compilation) of optimization passes, so if GCC did no optimization, it won’t be able to emit any code. Think of it another way: the input language to GCC is quite rich (even for plain C, where you … Read more