processor

问题 Floating point type represents a number by storing its significant digits and its exponent separately on separate binary words so it fits in 16, 32, 64 or 128 bits. Fixed point type stores numbers with 2 words, one representing the integer part, another representing the part past the radix, in negative exponents, 2^-1, 2^-2, 2^-3, etc. Float are better because they have wider range in an exponent sense, but not if one wants to store number with more precision for a certain range, for example

问题 Floating point type represents a number by storing its significant digits and its exponent separately on separate binary words so it fits in 16, 32, 64 or 128 bits. Fixed point type stores numbers with 2 words, one representing the integer part, another representing the part past the radix, in negative exponents, 2^-1, 2^-2, 2^-3, etc. Float are better because they have wider range in an exponent sense, but not if one wants to store number with more precision for a certain range, for example

问题 I executed a linear search on an array containing all unique elements in range [1, 10000], sorted in increasing order with all search values i.e., from 1 to 10000 and plotted the runtime vs search value graph as follows: Upon closely analysing the zoomed in version of the plot as follows: I found that the runtime for some larger search values is smaller than the lower search values and vice versa My best guess for this phenomenon is that it is related to how data is processed by CPU using

问题 I'm relatively new to learning programming languages, and I feel I have 20 to 25% of understanding of Object Oriented Programming Language, more specifically C# language. So I really state this question without knowing the actual significance of its answer, if any, to my process of learning the language, but I really felt I need to ask it. When a method is called for execution, I know that all its local variables and its parameters and return value are actually present in the stack memory.

问题 I have searched around to get the answers for these questions. but not much luck. Is it possible to run 32-bit code in a machine with 64-bit processor ? The answer seems to be yes. but there is a debate on performance issues, since 32-bits are left unused on the processor. Now my question is vice-versa, Is it possible to run 64-bit code in a machine with 32-bit processor? from my little understanding, the answer is NO, because the code designed to run on 64-bit will be using 64-process

问题 Hopping from Java Garbage Collection, I came across JVM settings for NUMA. Curiously I wanted to check if my CentOS server has NUMA capabilities or not. Is there a *ix command or utility that could grab this info? 回答1: I'm no expert here, but here's something: Box 1, no NUMA: ~$ dmesg | grep -i numa [ 0.000000] No NUMA configuration found Box 2, some NUMA: ~$ dmesg | grep -i numa [ 0.000000] NUMA: Initialized distance table, cnt=8 [ 0.000000] NUMA: Node 4 [0,80000000) + [100000000,280000000)

问题 Hopping from Java Garbage Collection, I came across JVM settings for NUMA. Curiously I wanted to check if my CentOS server has NUMA capabilities or not. Is there a *ix command or utility that could grab this info? 回答1: I'm no expert here, but here's something: Box 1, no NUMA: ~$ dmesg | grep -i numa [ 0.000000] No NUMA configuration found Box 2, some NUMA: ~$ dmesg | grep -i numa [ 0.000000] NUMA: Initialized distance table, cnt=8 [ 0.000000] NUMA: Node 4 [0,80000000) + [100000000,280000000)

问题 I am having Intel Core IvyBridge processor , Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz( L1-32KB,L2-256KB,L3-8MB). I know L3 is inclusive and shared among multiple core. I want to know the following with respect to my system PART1 : L1 is inclusive or exclusive ? L2 is inclusive or exclusive ? PART2 : If L1 and L2 are both inclusive then to find the access time of L2 we first declare an array(1MB) of size more than L2 cache(256KB) , then start accessing the whole array to load into L2 cache.

问题 I am having Intel Core IvyBridge processor , Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz( L1-32KB,L2-256KB,L3-8MB). I know L3 is inclusive and shared among multiple core. I want to know the following with respect to my system PART1 : L1 is inclusive or exclusive ? L2 is inclusive or exclusive ? PART2 : If L1 and L2 are both inclusive then to find the access time of L2 we first declare an array(1MB) of size more than L2 cache(256KB) , then start accessing the whole array to load into L2 cache.

问题 I am looking for things like reordering of code that could even break the code in the case of a multiple processor. 回答1: Wikipedia has a fairly comprehensive list of optimization techniques here. 回答2: The most important one would be memory access reordering. Absent memory fences or serializing instructions, the processor is free to reorder memory accesses. Some processor architectures have restrictions on how much they can reorder; Alpha is known for being the weakest (i.e., the one which can