NEVILLE%umass-cs.csnet@csnet-relay.arpa (Neville D. Newman) (04/11/86)
A couple or three weeks ago, i posted an inquiry here as to the availability of RAM disk drivers for 4BSD or Ultrix. i did in fact receive such a driver and it turns out that it was posted to net.sources a year and a half ago (Nov. 84 if you want to check your archives). However the person who sent it to me made the same comment that i received from about 6 other people - using extra RAM for disk buffers would be better (along with setting the sticky bit on target files). The rest of this posting refers to using the disk-buffer solution. It was also suggested that /etc/update (performs regular sync()'s) be changed to sync() less often than the norm, which is every 30 seconds. i grabbed the source from our BSD machine and modified it to take an optional overriding argument specifying the period in seconds. You don't really need the source, as it is a trivial program to reproduce. Just set periodic alarms, and have the signal handler open important system and local directories like /bin, /local, etc. The way i found to change the size of the buffer space is to change the initialization values of nbuf and bufpages in /vmunix using adb -w . No one who responded mentioned how they did it, but without source for this machine our choices are rather limited! We have not done this yet on anything more than an exploratory basis but based on the report from the message file and the 4BSD source we casually perused, we managed to probe both sides of the "point of diminishing returns". The first two changes gave very small increases because we only changed bufpages; the third time we overshot and the boot configured with only 2Meg. We'll get it yet. Anyway, thanks to those who responded especially John Gilmore. -neville Internet: neville@umass.csnet