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Unformatted text preview: uld happen if we DIDN’T add this feature?
Optimize useful things, not rarely used features
good enough is good enough
optimize the common case: example? Performance
Memory and CPU tradeoff
Use macros to save function call overhead
#define max(a,b) a<b
Keep critical regions as small as possible Performance
Caching: e.g. i-node cache
To look up /usr/ast/mbox requires:
1. read i-node for root dir, 2. read the root dir, 3. read the i-node for
/usr, 4. Read the /usr dir, 5. Read the i-node for /usr/ast, 5. read the
/usr/ast/dir Other examples of caching? Performance
Caching exploits locality: temporal and spatial
Other Examples of exploiting locality? Execution
OS mechanisms should “hang together”
Role of OS is a coordinator of user activities (threads) and generator
of events Execution
Execution Paradigms (cont’d)
Algorithmic Role of OS is a service provider Systems
Be clever at high utilization!
simple techniques work well at “low resource demands”
Bulk operations work better than large number of smaller ones
Indirection, indirection, …. That’s
That’s All Folks
Good luck on the final!
Weds July 28 in the classroom, 12:20-2:20...
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- Summer '14
- Operating Systems