Lecture22nFull(1) - Click to edit Master subtitle style...

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Unformatted text preview: Click to edit Master subtitle style 9/16/11 Lecture 22 COT 4600 Operating Systems Spring 2011 Dan C. Marinescu Office: HEC 304 Office hours: Tu-Th 5:00-6:00 PM Lecture 22 9/16/11 Lecture 22 - Tuesday April 12, 2011 n Last time: Scheduling n Today: Memory characterization Multilevel memories management using virtual memory Adding multi-level memory management to virtual memory Page replacement algorithms n Next Time: Performance Lecture 22 22 Lecture 22 9/16/11 Virtual memory n Several strategies Paging Segmentation Paging+ segmentation n At the time a process/thread is created the system creates a page table for it; an entry in the page table contains The location in the swap area of the page The address in main memory where the page resides if the page has been brought in from the disk Other information e.g. dirty bit. n Page fault & a process/thread references an address in a page which is not in main memory n On demand paging & a page is brought in the main memory from the swap area on the disk when the process/thread references an address in that page. Lecture 22 33 Lecture 22 9/16/11 Lecture 22 44 Lecture 22 9/16/11 Lecture 22 55 Lecture 22 9/16/11 Dynamic address translation Lecture 22 66 Lecture 22 9/16/11 Multi-level memories Lecture 22 77 Lecture 22 9/16/11 System components involved in memory management n Virtual memory manager VMM & dynamic address translation n Multi level memory management MLMM & Lecture 22 88 Lecture 22 9/16/11 The modular design n VM attempts to translate the virtual memory address to a physical memory address n If the page is not in main memory VM generates a page-fault exception . n The exception handler uses a SEND to send to an MLMM port the page number n The SEND invokes ADVANCE which wakes up a thread of MLMM n The MMLM invokes AWAIT on behalf of the thread interrupted due to the page fault. n The AWAIT releases the processor to the SCHEDULER thread. Lecture 22 99 Lecture 22 9/16/11 A p p lica tio n th re a d 1 V irtu a l M e m o ry M a n a g e r E xce p tio n H a n d le r S ch e d u le r M u lti-L e ve l M e m o ry M a n a g e r A p p lica tio n th re a d 2 IR P C T ra n sla te (P C ) in to (P a g e # ,D isp l) Is (P a g e# ) in p rim a ry sto ra g e ? Y E S- co m p u te th e p h ysica l a d d re ss o f th e in stru ctio n IR P C N O p a g e fa u lt S a ve P C H a n d le p a g e fa u lt Id e n tify P a g e # Issu e A W A IT o n b e h a lf o f th re a d 1 A W A IT S E N D (P a g e # ) T h re a d 1 W A IT IN G T h re a d 2 R U N N IN G IR P C L o a d P C o f th re a d 2 F in d a b lo ck in p rim a ry sto ra g e Is d irty b it o f b lo ck O N ? Y E S- w rite b lo ck to se co n d a ry sto ra g e N O - fe tch b lo ck co rre sp o n d in g to m issin g p a g e I/O o p e ra tio n co m p le ts A D V A N C E T h re a d 1 R U N N IN G L o a d P C o f th re a d 1 IR P C Lecture 22 1010 Lecture 22 9/16/11 Name resolution in multi- level memories n We consider pairs of layers:...
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This note was uploaded on 09/16/2011 for the course COP 4600 taught by Professor Montagne during the Spring '08 term at University of Central Florida.

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Lecture22nFull(1) - Click to edit Master subtitle style...

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