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What is the use of the DMA controller in a processor?
From Wikipedia: Direct memory access (DMA) is a feature of computerized systems that allows certain hardware subsystems to access main system memory independently of the central processing unit (CPU). [...] A DMA controller can generate memory addresses and initiate memory read or write cycles. It contains several processor registers that can be written and read by the CPU. These include a mem

Categories : Performance

JavaFX Table with highlighted text (Labels) with poor performance
For my solution to work you need to move some parts around. Especially the logic of searching and splitting should be moved out of the Renderer as it is not really GUI related work.. So lets assume the following data class for your TableView (where dataNumber and dataString) are just random properties of other TableColumns: public class MyTableData { private final IntegerProperty dataNumber = n

Categories : Performance

Why is swift's character comparison so slow?
I found your question very interesting, and I go deeper with the Swift Documentation, so here is my supposition : Character type is a Unicode scalar (21-bit number), so when you test charA == charB, the CPU is comparing two Unicode scalar. String is a collection of Unicode scalar, so when you test stringA == stringB, the CPU is comparing the hashcode the collection, so it's more lighweight than

Categories : Performance

Fastest server to server communication solution
I would recommend a REST web service, mostly because they are a lightweight industry standard. You're not giving us very many details though, and the data you are returning is so minimal that there is not likely a significant difference. Look into web server optimization practices, like enabling GZIP, which will make more of a difference.

Categories : Performance

Improve download/delete speed of large chunked files in Openstack Swift
The issue was related to the stack provider, as of networking problems all deletes on the openstack cloud were slow. As the file consisted of many chuncks, the deletion of the whole file became extremely slow.

Categories : Performance

SVG SMIL or RequestAnimationFrame animation
Sarah Drasner wrote a wonderful guest post about this on CSS Tricks: Weighing SVG Animation Techniques (with Benchmarks). It's definitely worth to take a look at it.

Categories : Performance

Should small games use UDP or TCP if only a few packets are critical?
According to me, First of all know what TCP offers over UDP Flow control Order Security and Reliability i.e. established connection If above things are not important or doesnt matter for you (If you are handling these in your code) then use udp else tcp is best option. You will get very less performance/network improvement with UDP in small scale usage. TCP is always better.

Categories : Performance

Sorting a stack using another stack
Looks O(n^2) to me. I'm guessing that an already-sorted stack has the worst-case performance. I counted the number of times that s.push gets executed, given an already-sorted stack of a particular size. Stack of size 1. backpushes: 0 Stack of size 2. backpushes: 1 Stack of size 3. backpushes: 3 Stack of size 4. backpushes: 6 Stack of size 5. backpushes: 10 Stack of size 6. backpushes: 15 Stack of

Categories : Performance

JMeter: Can't copy CSV variable into another variable
If you have 3 requests, I suggest you put a Beanshell preprocessor on the first request, which copies the CSV_ACCESS_TOKEN to ACCESS_TOKEN. Each of your samples can the use ACCESS_TOKEN, so CSV is accessed once per cycle of 3. Each time the preprocessor run (ie before each 1st request), CSV_ACCESS_TOKEN will get updated from the dataset. If it is the same request, which you do not wish to dupli

Categories : Performance

Docker Run Time Statistics ( Benchmarks)
a): A container is like a process. This question is like asking "how many processes can I run in parallel". It is not answerable without knowing what the processes are doing. Please add this information to your question. b) Both 3.5GB and 6.5GB are very large for a Docker image. Best practice is to put one application in one container: if you have an application that size, then great. If no

Categories : Performance

How to measure the performance of a file server
Really, it doesn't make any difference. Your limiting factors for file serving are IO. Disk or network. Protocol overhead makes a difference in some cases too. But the implementation of that protocol is unlikely to be a bottleneck. If you really want to benchmark it, then what you need to do is look at the workload you'll be using. Are you transferring big files or little ones? Is transfer s

Categories : Performance

Best algorithm to sort linked list based patient's seriousness and arrival time?
To sort linked list, the most often used method is merge sort because it is easy to implement with linked list and it's one of the best comparison-based sorting algorithm. When you say if both patient have same seriousness, then arrival time is use to compare., it means you need a stable sort, and merge sort is stable, so give it a try.

Categories : Performance

Determining running time of algorithm
Let T_k denote the time it takes to run ALG-1 on input of size n = 2^k. I'm going to assume that your ALG-2(B, C) means ALG-2 run on the concatenation of B and C, which is of length n. Then, it looks like you have the recurrence T_k = T_{k - 1} + sqrt(n / 2) + sqrt(n) = T_{k - 1} + C * sqrt(2^k), where C is a constant. If you keep expanding that out by writing T_{k - 1} in terms of T_{k - 2}, e

Categories : Performance

Cycles per Instruction - Does a line of code in assembly sum different cpi operation?
Cycle counting doesn't really work anymore, ever since the Pentium 4 hit the market. Deep pipelines, three-level memory cache hierarchies, multiple execution units with out-of-order execution, branch prediction... It is often possible to make a good guess about the timing of a bigger piece of code but for two isolated instructions it is virtually impossible (unless one instruction happens to be D

Categories : Performance

Vaadin slow in Internet Explorer
The problem comes because you are using so many listeners in your components, and communication tends to collapse, so, try to handle the listeners in a way you don't and them to many components. In the other hand, as far as I tested vaadin, not removing the components after they are not used, causes the DOM to crash. I mean, if you don't need a component, why to show it?, it will consume a lot of

Categories : Performance

Can we replace existing null data with '' (Blank) to use indexes in oracle query
Thank you a_horse_with_no_name for comment. You are correct Null and '' both are considered as Null. So My second query uses index, but not considered the null value. I have verified with below code. -- Both are considered as null Select * from (SELECT '' as a,'b' as b FROM DUAL union select null , 'b1' from dual ) where a is null --No Row return select * from (SELECT '' as a,'b' as

Categories : Performance

Tools to help prove to a customer web application latency is from their network
I dont think you need to prove this to anyone, If you customer is in China and accessing application hosted in UK then obviously latency is major performance factor. what you can do is get time of your method using any profiler(maybe google search will help you in this) and get execution time of your method in below environments, In your local development environment (Lowest time) In your loca

Categories : Performance

How to distribute number of users for different HTTP Requests?
Yes, You can do it with synchronizing timer but only for a request and not with multiple request. but a tweak is possible with which you can achieve your desired load. 1. suppose you have 2 threadgroups having 1 request each. i.e. firstrequest and secondrequest 2. create synchronizing timer as a child of testplan (by this it will be applicable to both threadgroups) 3. put no. of threads to gro

Categories : Performance

Theoretical VS Practical running time evaluation
What O(N^4) means is that no matter how big N gets, the running time will always be less than or equal to a curve of the form C+K*N^4, where C and K are arbitrary constants. So, other than some sort of mathematical proof, possibly by recurrence relations, the only method is experimental. So you throw a series of datasets at it, with N varying across a range of magnitudes, and plot the running tim

Categories : Performance

Storing a 32 byte object, on Ivy Bridge?
I did a Web search, and it appears that Intel does not guarantee that a 32 byte write is atomic. I found this which suggests that not even regular 8 byte writes are guaranteed atomic. Intel provides the compare and exchange 8 byte instruction which is atomic. Bottom line is that I think you will need to take another approach. EDIT: I forgot about the x86 lock prefix. Looking at this, it says

Categories : Performance

Optimizing rank computation for very large sparse matrices
I don't know which algorithm is best suited for you and I agree that may be more appropriate to ask on math.stackexchange.com. While I was trying with the random matrix you supply G = sparse(randi(2,1000,1000))-1; I noticed that there is little chance that its rank is <1000, and whatever algorithm you use, it is likely that its performance is very data-dependant. For instance using eigs(G) on a

Categories : Performance

Branch alignment in x86-64 assembler
From what I can see in your algorithm, there is certainly not much you can do to improve it. The problem you are hitting is probably not so much the branch to an aligned position, although that can still help, you're current problem is much more likely the pipeline mechanism. When you write two instructions one after another such as: mov %eax, %ebx add 1, %ebx In order to execute the seco

Categories : Performance

GoLang Pointer Performance
Running the benchmark with the -m gcflag gives the possible answer: ./main_test.go:16: BenchmarkWithoutPointer []int literal does not escape (...) ./main_test.go:25: []int literal escapes to heap Your []int in the second example escapes to heap, which is slower than stack. If you use separate x and y fields for your arguments instead of a slice type Adder struct { x, y int } func (a *Adde

Categories : Performance

How can I make this big nasty query more efficient?
If you move the filtering to the where clause there will be less rows to be joined. Change this: group by ... HAVING SRC.SAP_SETNODE.SUBSET_CLS = '0101' AND SRC.SAP_SETNODE.SET_NAME = 'SISW.' || get_fy_part('YEAR', clock_timestamp()) to where SRC.SAP_SETNODE.SUBSET_CLS = '0101' AND SRC.SAP_SETNODE.SET_NAME = 'SISW.' || get_fy_part('YEAR', clock_timestamp()) group by ...

Categories : Performance

How about performance for the $near operation in mongodb(meteor)
The best answer lies in the mongodb source code in github (obviously! duh!). According to the documentation, its important to ensure the indexes. Link: http://docs.mongodb.org/manual/core/geospatial-indexes/

Categories : Performance

Fortran: Matrix value changing when using CGESV from LAPACK
Changing this do 1 i=1,1000 Atemp = A(:,:,i) !takes about 2.5 sec to compute CGESV(x,x,Atemp,x,x,b,x,x) 1 continue to this atemp = a do i=1,1000 CGESV(x,x,atemp(:,:,i),x,x,b,x,x) end do may well show a slight improvement in execution speed. Not due to the modernisation of the loop statements but due to the single, large, copy rather than the repeated smaller copies. T

Categories : Performance

how to simulate 1000 concurrent user using jmeter
Number of Threads- The maximum number of users you want to run. Ramp-Up Period - Defines how long it takes for JMeter to ramp up from zero users to X number of threads. It is in terms of seconds. Loop Count - Defines how many times you want each user to run your script. Other thing is that No. of user depends on your machine CPU , RAM , Physical memory. As far as I know using normal system you

Categories : Performance

Lua 5.1 # operator and string comparisons (performance)
Lua strings are stored in a table to avoid creating duplicates of the same strings, so every time a string is created it needs to be hashed and compared to anything with the same hash value as part of it's creation. The comparison of string objects after creation is O(1) as Lua already ensured they reference a unique string so Lua just compares the underlying pointers. as all string are inter

Categories : Performance

MATLAB Optimisation of Weighted Gram-Schmidt Orthogonalisation
1) My first attempt at vectorization: function [Q, R] = Gram_Schmidt1(A, w) [m, n] = size(A); Q = complex(zeros(m, n)); R = complex(zeros(n, n)); for j = 1:n v = A(:,j); QQ = Q(:,1:j-1); QQ = bsxfun(@rdivide, bsxfun(@times, w, conj(QQ)), w.' * abs(QQ).^2); for i = 1:j-1 R(i,j) = (v.' * QQ(:,i)); v = v - R(i,j) * Q(:,i);

Categories : Performance

My Prestashop is slow - how can I make it faster?
Check the Cache in Performance and put it to Memcached for example if it's not already. Also use a PHP Profiler to check the performance and resolve any issues according to the results. There's also a very important point which is the slow performance of the function file_exists PS validator insists on replacing file_exists with Tools::file_exists_cache /** * file_exists() wrapper with cache to

Categories : Performance

Image contrast estimation. How to speed up this code?
One way could be building an image of the mean using a window size of 5x5, then a local standard deviation filter with a window size of 5x5. After this is done you can calculate the result fairly quickly. M = imread('image.tif'); h = fspecial('average', 5); mean_im = filter2(M, h); std_im = stdfilt(M, 5); KPic = std_im ./ mean_im;

Categories : Performance

Classifying points in accordance with their coordinates
I have no access to MATLAB now, but roughly it would be something like this: You can get the first group as follows, A= [1.6 2.13 3; 1.2 2.36 5; 1.4 2.4 6; 1.01 2.21 9] B = A(:,2); mean = (max(B)-min(B))/3; C = B - min(B); Group1 = A(C<mean,:) then make the new matrix from the remaining rows as follows A = A(C>=mean,:) and then repeat until isempty(A) == true. There are many optimizat

Categories : Performance

Why is std::pair faster than std::tuple
You are missing some crucial information: What compiler do you use? What do you use to measure the performance of the microbenchmark? What standard library implementation do you use? My system: g++ (GCC) 4.9.1 20140903 (prerelease) GLIBCXX_3.4.20 Anyhow, I ran your examples, but reserved the proper size of the vectors first to get rid of the memory allocation overhead. With that, I funnily obs

Categories : Performance

WCF hosted in IIS peformance issue during load test
I have found an answer in kb aritcle number 2538826, the sample code also can be found in this blog post (with some additional information like how to add perf counters and write load test). This solution will help you only if you have the described behavior (check provided links for details): number of threads you use (Thread count perf counter) does not scale as fast as your requests. The pictu

Categories : Performance

Faster way of testing a condition in MATLAB
Not sure which one will be faster (that may depend on the machine and Matlab version), but here are some alternatives to all(v<0): ~any(v>0) nnz(v>=0)==0 %// Or ~nnz(v>=0) sum(v>=0)==0 %// Or ~sum(v>=0) isempty(find(v>0, 1)) %// Or isempty(find(v>0))

Categories : Performance

Massive performance loss when using IBM JVM on AIX 7
You have 3 issues. Your processor architecture Your operating system choice Your JVM provider Of these, the biggest impact in this case will be the IBM JRE which has really poor performance for loops. Were you doing file work, you'd find it was slow due to the operating system. There are many many causes of slowness with this combination, your best bet is to move to x86, Linux and Oracle.

Categories : Performance

Can someone explain the strange increase in performance of MPI_reduce when I increase number of nodes on Cray
I had a similar performance problem while working on Cray for my research project and I discussed it with my advising professor. One of the reason for this result could be the optimization when more than specific number of nodes are utilized.This optimization could result into better performance than 2 or 3 nodes although it should have been worst. Try using different number of nodes (i.e increa

Categories : Performance

Choosing random lines from file takes too long in BASH
Just use shuf to select the lines, which is what it was designed for. For example (see note): readarray users < <(shuf -n $1 "$2") readarray pages < <(shuf -n $1 "$2") for (( i = 0; i < $1; i++ )); do echo L ${users[i]} ${pages[i]} done for (( i = 0; i < $1; i++ )); do echo U ${users[i]} ${pages[i]} done This will still be slow, because shuf needs to read the entire

Categories : Performance

Can I calculate TP,TN, FPR and FNR in multiclass
You can calculate these values per class and then aggregate them if you wish to do so. In the calculation for one class you treat the class as the "true" and the union of the other classes as "false". To aggregate for an overall value I would suggest to use the median, which is less sensitive to outliers.

Categories : Performance




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