context-switch

问题 Originally I believed the overhead to a context-switch was the TLB being flushed. However I just saw on wikipedia: http://en.wikipedia.org/wiki/Translation_lookaside_buffer In 2008, both Intel (Nehalem)[18] and AMD (SVM)[19] have introduced tags as part of the TLB entry and dedicated hardware that checks the tag during lookup. Even though these are not fully exploited, it is envisioned that in the future, these tags will identify the address space to which every TLB entry belongs. Thus a

问题 I\'m writing a small program in C, and I want to measure it\'s performance. I want to see how much time do it run in the processor and how many cache hit+misses has it made. Information about context switches and memory usage would be nice to have too. The program takes less than a second to execute. I like the information of /proc/[pid]/stat, but I don\'t know how to see it after the program has died/been killed. Any ideas? EDIT: I think Valgrind adds a lot of overhead. That\'s why I wanted

问题 Could any one tell me what is exactly done in both situations? What is the main cost each of them? 回答1: The main distinction between a thread switch and a process switch is that during a thread switch, the virtual memory space remains the same, while it does not during a process switch. Both types involve handing control over to the operating system kernel to perform the context switch. The process of switching in and out of the OS kernel along with the cost of switching out the registers is