prefetch

问题 I tried the following code: RootPanel root = RootPanel.get("root"); root.clear(); final FlowPanel p = new FlowPanel(); root.add(p); for (int i=0; i<20; ++i) { String url = "/thumb/"+i; final Image img = new Image(url); img.addLoadHandler(new LoadHandler() { @Override public void onLoad(LoadEvent event) { p.add(img); } }); Image.prefetch(url); But it does not work for me. Did I missed something? 回答1: Image load handler is called only in the case, when image is attached to the DOM. So you have

问题 I am getting Error while trying to disable Hardware prefetcher in my Core i7 system. I am following the method as per the link How do I programmatically disable hardware prefetching? In my system grep -i msr /boot/config-$(uname -r) CONFIG_X86_DEBUGCTLMSR=y CONFIG_X86_MSR=y CONFIG_SCSI_ARCMSR=m Here is my error message root@ ./rdmsr 0x1a0 850089 [root@ ./wrmsr -p 0 0x1a0 0x850289 (to disable hardware prefetcher in Core i7) wrmsr:pwrite: Input/output error I am getting same error for disabling

问题 I am trying to speed up a single program by using prefetches. The purpose of my program is just for test. Here is what it does: It uses two int buffers of the same size It reads one-by-one all the values of the first buffer It reads the value at the index in the second buffer It sums all the values taken from the second buffer It does all the previous steps for bigger and bigger At the end, I print the number of voluntary and involuntary CPU In the very first time, values in the first buffers

问题 Let's say I have two different apps : teacher/models.py: Teacher(models.Model): name = models.CharField(max_length=300) class/models.py: Class(models.Model): name = models.CharField(max_length=300) teacher = models.ForeignKey(Teacher) students = models.ManyToManyField(Student) I want to get all the teachers with classes and all classes attached. The result I want: {[ teacher: '3L' #Teachers Id classes: ['20L','14L','30L'] #list of Class objects or ids with the above teacher ], [# similar to

问题 Extending my previous question on stack-overflow. I have four tables: A <--- Relation ---> B ---> Category (So the relation between A and B is n to n, where the relation between B and Category is n to 1) Relation stores 'Intensity' of A in B. I need to calculate the intensity of A in each Category and find the Maximum result. It is achievable using: A.objects.values( 'id', 'Relation_set__B__Category_id' ).annotate( AcIntensity=Sum(F('Relation_set__Intensity')) ).aggregate( Max(F('AcIntensity'

问题 Recently I have been observing performance effects in memory-intensive workloads I was unable to explain. Trying to get to the bottom of this I started running several microbenchmarks in order to determine common performance parameters like cache line size and L1/L2/L3 cache size (I knew them already, I just wanted to see if my measurements reflected the actual values). For the cache line test my code roughly looks as follows (Linux C, but the concept is similiar to Windows etc. of course):

问题 Given a JSON API endpoint /api/config , we're trying to use <link rel="prefetch" href="/api/config"> in the head of an HTML document. Chrome downloads the data as expected when it hits the link tag in the HTML, but requests it again via XHR from our script about a second later. The server is configured to allow caching, and is responding with Cache-Control: "max-age=3600, must-revalidate" in the header. When Chrome requests the data again, the server responds correctly with a 304 Not Modified

问题 Has anyone had experience using prefetch instructions for the Core 2 Duo processor? I've been using the (standard?) prefetch set ( prefetchnta , prefetcht1 , etc) with success for a series of P4 machines, but when running the code on a Core 2 Duo it seems that the prefetcht(i) instructions do nothing, and that the prefetchnta instruction is less effective. My criteria for assessing performance is the timing results for a BLAS 1 vector-vector (axpy) operation, when the vector size is large

问题 What is the cost of a late prefetch done with a __builtin_prefetch(..., 1) intrinsic (prefetch in preparation for a write)? That is, a prefetch that does not arrive in the L1 cache before the demand load or write that requires it? For example void foo(std::uint8_t* line) { __builtin_prefetch(line + std::hardware_constructive_interference_size, 1); auto next_line = calculate_address_of_next_line(line); auto result = transform(line); write(next_line, result) } In this case if the cost of

问题 What is the cost of a late prefetch done with a __builtin_prefetch(..., 1) intrinsic (prefetch in preparation for a write)? That is, a prefetch that does not arrive in the L1 cache before the demand load or write that requires it? For example void foo(std::uint8_t* line) { __builtin_prefetch(line + std::hardware_constructive_interference_size, 1); auto next_line = calculate_address_of_next_line(line); auto result = transform(line); write(next_line, result) } In this case if the cost of