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