Path: utzoo!attcan!uunet!lll-winken!ncis.llnl.gov!ncis!helios.ee.lbl.gov!pasteur!ames!killer!rpp386!jfh From: jfh@rpp386.Dallas.TX.US (John F. Haugh II) Newsgroups: comp.unix.wizards Subject: Re: Time slicing -- How does 4.3bsd do it? Message-ID: <11263@rpp386.Dallas.TX.US> Date: 18 Jan 89 15:03:45 GMT References: <1798@maccs.McMaster.CA> <15504@mimsy.UUCP> Reply-To: jfh@rpp386.Dallas.TX.US (John F. Haugh II) Distribution: na Organization: River Parishes Programming, Dallas TX Lines: 21 In article <15504@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes: >Thus, if by `quantum' you mean the typical scheduler quantum, the value >is essentially random, depending on when the process was scheduled with >respect to the constant 100 ms ticks. In the UNIX idiom the answer would be 100ms. Every 100ms you get a chance to lose the CPU, but not more often [ baring a process being awoken on a higher priority ]. Older kernels used a 1 second quantum. I suspect this is what prompted the question. > In the absence of clock-related >voluntary context switching, the unfairness should average out to the >point where it can be ignored, but that absence is not guaranteed. All scheduling is unfair. Doesn't the joke go "If this is timesharing I want my share now."? -- John F. Haugh II +-Quote of the Week:------------------- VoiceNet: (214) 250-3311 Data: -6272 |"UNIX doesn't have bugs, InterNet: jfh@rpp386.Dallas.TX.US | UNIX is a bug." UucpNet : !killer!rpp386!jfh +--------------------------------------