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Inside Microsoft Windows 2000 7. Memory Management

Inside Microsoft Windows 2000 7. Memory Management System Memory Pools Apr. 18, 2001 DB Lab 박동철 System memory pools(cont.) 2 types Non-paged pool Ranges of system virtual address that are guaranteed to reside in physical memory at all times

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Inside Microsoft Windows 2000 7. Memory Management

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  1. Inside Microsoft Windows 20007. Memory Management System Memory Pools Apr. 18, 2001 DB Lab 박동철

  2. System memory pools(cont.) • 2 types • Non-paged poolRanges of system virtual address that are guaranteed to reside in physical memory at all times • Paged poolRegion of virtual memory in system space that can be paged in and out of the system 7: Memory Management

  3. System memory pools • 2 types of non-paged pools • General use • Emergency use • Single-processor system • 3 paged pools • Multi-processor • 5 paged pools 7: Memory Management

  4. Look-aside Lists (cont.) • Basic difference between memory pools and look-aside pools • Memory pool • Variable sized blocks • Flexible • Look aside pool • Fixed sized blocks • Faster 7: Memory Management

  5. Look-aside Lists (cont.) • Executive components and device driver can make look-aside lists • Several executive subsystems create • Separate look-aside lists for each processor • A general per-processor paged and non-paged look-aside list for small allocations 7: Memory Management

  6. Look-aside Lists • Empty, or having freed structure? • The system allocates from paged or non-paged pool or allocation can be satisfied very quickly • Pool allocation routine tunes the # of freed buffers once per second • Increased if frequent • Reduced if not frequent 7: Memory Management

  7. Driver Verifier • Can be used to help find and isolate commonly found bugs in device driver or other kernel-mode system code. • Consists of support in several system components 7: Memory Management

  8. Driver Verifier Configuration and Initialization • Driver settings are stored in the registry • Contains a bitmask for verification types enabling • 4 memory-related verification options • Special Pool, Pool tracking, force IRQL Checking. Low Resources simulation 7: Memory Management

  9. Special Pool • Causes a kernel mode access violation • Gets the finger pointer at the buggy driver • Causes some additional validation checks to be performed when a driver allocates or frees memory 7: Memory Management

  10. Pool Tracking (cont.) • When enabled • The pool allocation routines associate an optional 4-letter tag with memory the driver allocates • The memory manager checks at driver unload time whether the driver freed all the memory allocations it made. 7: Memory Management

  11. Pool Tracking • Usage of monitoring driver memory • To detect memory leaks • To detect the errors caused by memory de-allocation no longer required 7: Memory Management

  12. Force IRQL Checking • One of the most common device driver bugs • Occurs at elevated IRQL • Memory manager can’t service a page fault when the IRQL is DPC/dispatch level or above • Difficult to test above bug • Force IRQL checking option is helpful to identify the faulty driver 7: Memory Management

  13. Low Resources simulation • Causes Driver Verifier to randomly fail memory allocations that verified device drivers perform • Low resources can be ignored? • Beginning 7 minutes after system boots Driver verifier starts randomly failing allocation calls for device drivers 7: Memory Management

  14. Address Space Layout (cont.) 7: Memory Management

  15. Address Space Layout (cont.) • Windows 2000 • 2G or 3GB private address space • Windows 2000 Advanced Server, Windows 2000 Datacenter Server • 3GB private address space • The AWE functions provide better solution to the need for more data 7: Memory Management

  16. Address Space Layout (cont.) • How can we use full 3GB address space? • /LARGEADDRESSAWARE linker flag  IMAGE_FILE_LARGE_ADDRESS_AWARE flag set in the image header • use /3GB switch when boot Windows 2000 Advanced Server, Windows 2000 Datacenter Server • How about using /3GB on Windows 2000? 7: Memory Management

  17. Virtual Address Space in Consumer Windows • A bit different from Windows 2000 • Application-wide 2-GB private address space • System-wide 1-GB system space • System-wide 1-GB shared memory sections 7: Memory Management

  18. System Address Space Layout (cont.) 7: Memory Management

  19. System Address Space Layout (cont.) • System code • O/S image, HAL, device drivers to boot system • System mapped views • Win32k.sys • Session space 7: Memory Management

  20. System Address Space Layout (cont.) • Hyperspace • Process working set list and other physical pages • System working set list • System cache paged pool • Pageable system memory heap • System page table entries 7: Memory Management

  21. System Address Space Layout (cont.) • Non-paged pool • Non-pageable system memory heap • Crash dump information • HAL usage 7: Memory Management

  22. System Address Space Layout (cont.) • Session space • What is session? • Session-specific paged pool area used by the Win32k.sys • Win32 subsystem process(csrss.exe) • Logon process(winlogon.exe) • Session manager process(smss.exe) 7: Memory Management

  23. Address translation 7: Memory Management

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