IN CLASS NOTES FOR APRIL
Fri, April 16 :-
Conclude on Chapter about files. A rough explaination on Layers of I/O from the virtual machine layers and the I/O function aspect. Learned that the smallest unit in a disk is called a sector. Then, 2 sectors or more will for a block. 2 blocks form a cluster. In UNIX system, a cluster termed as a Zone.Covered Contiguous File, Block-Chained File, Table Mapped File, and Index Blocked File System Structure.
Wed, April 14 :-
Introduction to File System. Learned about the difference between file manipulation, directory manipulation, Volume/Media and Program-Level Interface. All information needed bt the job including system files, must be submitted with the batch job.
A file is needed for presistance storage. Will not be erased when system shuts down.
In UNIX, there are 3 main categories of files, they are directory, regular, and special files to link to drivers.
Mon, April 12 :-
About segmentation. A page has a fix size while a segment has variable size.
The major difference between a segmentation with paging address formats & pure segmentation address format is that pure segmentation will only load the segments needed into memory. Using less resources and avoid wasting memory for more useful functions.
Also, talked a little about Dynamic Link Library files.
Fri, April 9 :-
Continuation from Static page replacement algorithm. This time finishing up on 2nd chance (a modified FIFO) which requires a hardware reference bit.
Dynamic page replacement Algorithms consist of theoratical, Classical , Practical and page fault frequency.
Wed, April 7 :-
Discussed about Optimum Page replacement algorithm.
Note that less page = less search to bring things/ data in or out. Thus, the more page fault, the slower the access will be because it needs to constantly read from disk.
FIFO has an anomaly called Belady's anomaly ( something not expected ). Stated that the more page frames there is, the more page fault exist.
Explained how LRU (least recently used) & NRU/NUR (not recently used/ not used recently) works.
Mon, April 5:-
~ Absent from class ~ ECE 350 lab work
Fri, April 2:-
~ Class cancelled by lecturer ~