tlb

问题 I'm trying to understand the meaning of the perf events: dTLB-loads and dTLB-stores? 回答1: When virtual memory is enabled, the virtual address of every single memory access needs to be looked up in the TLB to obtain the corresponding physical address and determine access permissions and privileges (or raise an exception in case of an invalid mapping). The dTLB-loads and dTLB-stores events represent a TLB lookup for a data memory load or store access, respectively. The is the perf definition of

问题 I'm trying to understand the meaning of the perf events: dTLB-loads and dTLB-stores? 回答1: When virtual memory is enabled, the virtual address of every single memory access needs to be looked up in the TLB to obtain the corresponding physical address and determine access permissions and privileges (or raise an exception in case of an invalid mapping). The dTLB-loads and dTLB-stores events represent a TLB lookup for a data memory load or store access, respectively. The is the perf definition of

问题 Is TLB hierarchy inclusive on modern x86 CPU (e.g. Skylake, or maybe other Lakes)? For example, prefetchtn brings data to the level cache n + 1 as well as a corresponding TLB entry in DTLB. Will it be contained in the STLB as well? 回答1: AFAIK, on Intel SnB-family 2nd-level TLB is a victim cache for first-level iTLB and dTLB. (I can't find a source for this and IDK where I read it originally. So take this with a grain of salt . I had originally thought this was a well-known fact, but it might

问题 I'm currently developing a "drop-in" replacement of an old COM interface (which is used to communicate with other devices). This interface is currently used in a big application. The old COM interface is now deprecated by the author of the library they now only support and develop a C# interface. My task is to develop the above mentioned "drop-in" replacement. Which acts as a proxy between the old application (written in Delphi) and the new C# based interface. Im trying to have as little as

问题 Is there a decent guide explaining how to use the TLB ( Translation Lookaside Buffers ) tables on an ARM1176JZF-S core? Having looked over the technical documentation for the that ARM platform I still have no clue what a TLB is or what it looks like. As far as I understand, each TLB entry maps a virtual page to a physical page, allowing remapping and controlling memory permissions. Apart from that, I have absolutely no clue on how to use them. What structure does a TLB entry have? How do I

问题 Is there a decent guide explaining how to use the TLB ( Translation Lookaside Buffers ) tables on an ARM1176JZF-S core? Having looked over the technical documentation for the that ARM platform I still have no clue what a TLB is or what it looks like. As far as I understand, each TLB entry maps a virtual page to a physical page, allowing remapping and controlling memory permissions. Apart from that, I have absolutely no clue on how to use them. What structure does a TLB entry have? How do I

问题 What is the difference between Cache and Translation LookAside Buffer [TLB] ? 回答1: From Wiki: In computer science, a cache (pronounced /kæʃ/, kash) is a collection of data duplicating original values stored elsewhere or computed earlier, where the original data is expensive to fetch (owing to longer access time) or to compute, compared to the cost of reading the cache. In other words, a cache operates as a temporary storage area where frequently accessed data can be stored for rapid access.

问题 I have the following specifications of an ARM based SoC: L1 Data cache = 32 KB, 64 B/line, 2-WAY, LRU L2 Cache = 1 MB, 64 B/line, 16-WAY L1 Data TLB (for loads): 32 entries, fully associative L2 Data TLB: 512 entries, 4-WAY PDE Cache: 16 entries (one entry per 1 MB of virtual space) And I wonder what is the PDE cache? I guess it's something similar to TLB, but I'm not sure. Answer It seems that PDE (Page Directory Entry) is Intermediate table walk cache which indeed can be implemented

问题 I have been running some benchmarks on some algorithms and profiling their memory usage and efficiency (L1/L2/TLB accesses and misses), and some of the results are quite intriguing for me. Considering an inclusive cache hierarchy (L1 and L2 caches), shouldn't the number of L1 cache misses coincide with the number of L2 cache accesses ? One of the explanations I find would be TLB related: when a virtual address is not mapped in TLB, the system automatically skips searches in some cache levels.

问题 For Intel 64 and IA-32 processors, for both data and code independently, there may be both a 4KB TLB, and a Large Page (2MB, 1GB) TLB (LTLB). How does address translation work in this case? Would the hardware simply be able to access both in parallel, knowing that a double-hit can't occur? In the LTLBs, how would the entries be organized? I suppose, when the entry is originally filled from a page-structure entry, the LTLB entry could include information about how a hit on this entry would