Huseyin ABANOZ

Working Set  is the set of actively used pages. A process needs that amount of physical memory to run properly. If there is not enough physical memory, process will spent considerable amount of time to swapping. Thus performance will be degraded. If this problem is system wide, all process are hungry for physical memory, system will spent most of time to swapping witout any actual work. This is called  thrasing . Linux top Command for Process Memory Usage Column explanations from  Understanding Process memory : ·           RES  shows the actual physical RAM used by your process. ·           VIRT  shows the actual virtual memory reserved by your process. ·           DATA  shows the amount of virtual private anonymous memory reserved by your process. That memory may or may not be mapped to physical RAM. It c...

Introduction In simple and straightforward terms: Modern Operating Systems (OS) controls access to memory. Process demands memory and OS provides. Each process thinks it has a large consecutive space of memory which is called  virtual memory .  For a 32 bit system virtual address space is 4G wide. For a  64 bit system virtual address space size is 256TB . Virtual memory brings some very important advantages. Each process can address whole address space available; however, system may not have that much physical memory. Each process has its own private virtual memory space which other process cannot access. Virtual memory concept also lets operating system map files. Finally virtual memory concept sharing similar memory areas between processes. Paging Virtual address space is divided into small fixed size consecutive address blocks which are called  pages . Usually a page is 4 kilobytes in size. Similarly physical address space is divided into such blocks wh...