[net.rumor] Some words about 4.3

yee@ucbvax.ARPA (Peter E. Yee) (06/06/85)

From: kirk@ucbesvax (Kirk Thege)
To: cssg@ear
Subject: 4.3 seminar

Here is an outline of what Mike Karels talked about at the 4.3BSD seminar
he gave a few weeks ago.  I won't go into details but you can ask questions.
I couldn't read some of my notes, so fuzzy areas are marked with "?".

	-Kirk
------------------------------------

			4.3BSD Performance Improvements

Kernel Level
	- Pathname translation (was 40% of sys calls)
		o Cache directory offset ( ls is faster )
		o Cache recent filename inode
		o 85% combined cache hit ratio
		o 60% improvement in running time
		o 89% decrease in system time
	
	- Improved fragment extension algorithm
	- Intelligent terminal multiplexer siloing.
	- Faster clock interrupt switches.
	- Proc table management improved (enlarged table?)
	- Exec arg list copying by strings (not char by char)
	- Faster context switching
	- Network
		o More buffering (pipes faster), buffer sizes user specifiable
		o TCP round-trip tuning, signal size selection (?),
		  address selection (?)
		o Routing overhead
	
	- Macro expansions, in-lin expansions, faster hashing function
	- Code generator more efficient

User Level
	- Hashed host/passwd file -- name server to replace.
		o Mail is the big winner
	- Syslog ( did filesystem sync everytime )
	- Optimal routing process
	- Use of optimal buffering 
	- C strings routines cleaned up
	- inetd (cuts down on number of daemons)

System Configuration
	- Easier virtual memory configuration (17, 33, and 64Mb)
	- 64 Mb of physical memory
	- 255 mounted file systems (should hold CAD for a few months)
	- 8Gb filesystem sizes
	- Process segment size, removed 32Mb limit
	- Proc and text table limits increased form 1024 to 64000
	- Network
		o subnet addressing
		o addressing moved to protocol layer
	- Number of open files increased
	- Notification of changed window size info (from suns)
	- System error logging ( kernel/user level)
	- rdist
	- time synchronization service

System Security
	- Better control over access points ( mem, disks, devices)
	- Reduced use of setuid root programs, cautious use of library routines
	- Process tracing checks
	- Process group control in kernel
	- Configuration for more conservative environment


			4.4+ Possible Improvements

- Remote filesystems
- Stackable Protocols
- Real virtual memory
- Large address spaces
- Kernel VM - buffer cache, network buffers, proc table
- User access primitives - mmap, mremap, mumap, mprotect, madvise, mincore

------
							-Peter Yee
							..ucbvax!yee
							yee@Berkeley.ARPA