Deterministic Replay of Memory-mapped File Data for User-level programs

Abstract

Memory - mapped files allow to map a file on disk into a section in memory such that, when we fetch bytes from th at section of memory , the corresponding bytes of the file are read. Similarly, when we store data in the memory , the corresponding bytes are written to the file. This allows us to perform data trans fer more efficiently without using read or write system calls . This is especially useful when accessing data through memory - mapped I/O. Using memory - mapped files , a process can directly access the data without involving the kernel. This data can be of non - deterministic nature , e.g. , a camera sending some visual information. In order to record and replay a user - level program that accesses data through mem ory - mapped files, it is therefore important to account for this source of non - determinism. In this resear ch work, w e use memory protection mechanism and hardware breakpoints present in modern processors to detect whenever a process performs such a data transfer and inform the kernel so that it can record the non - deterministic data and then replay when desired .