Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!newstop!exodus!kessler From: kessler@hacketorium.Eng.Sun.COM (Tom Kessler) Newsgroups: comp.unix.internals Subject: Re: RAM disk. Message-ID: Date: 9 Oct 90 21:05:42 GMT References: <18560@rpp386.cactus.org> <143359@sun.Eng.Sun.COM> <18574@rpp386.cactus.org> <1850@necisa.ho.necisa.oz> <1990Oct09.121447.3336@virtech.uucp> Sender: news@exodus.Eng.Sun.COM Organization: Rocket Scientists Anonymous Lines: 19 In-reply-to: cpcahil@virtech.uucp's message of 9 Oct 90 12:14:47 GMT In article <1850@necisa.ho.necisa.oz> boyd@necisa.ho.necisa.oz (Boyd Roberts) writes: >When I hear `ram disk' I reach for my revolver. Now, repeat after me... > What is the buffer cache? -- A ram disk. >Increase NBUF and throw tmpfs away. Whoa, hold on there. There are some performance wins with tmpfs (once you get it working right :-) ) that you can't get by just upping NBUF (with the SunOS/System V R 4 memory management NBUF doesn't do what it used to do anyway :-) ). Remember that when you create and delete lots of shortlived files you've got to update their inodes (yes, I know i-nodes are cached as well as blocks). With the UFS file system you actually go to disk quite frequently (mostly for recover reasons). If you've marked this files system as a tmpfs the kernel doesn't have to worry about getting your stuff out to disk ever because presumably you don't care if the files are still there after a reboot. Maybe you could tweak the file system to "know this" but for whatever I've found tmpfs to speed up compiles quite a bit.