Date: Tue, 24 Jan 2006 17:45:36 -0500 From: John Baldwin <jhb@freebsd.org> To: "Poul-Henning Kamp" <phk@phk.freebsd.dk> Cc: current@freebsd.org, freebsd-arch@freebsd.org Subject: Re: [TEST/REVIEW] CPU accounting patches Message-ID: <200601241745.38514.jhb@freebsd.org> In-Reply-To: <24201.1138140983@critter.freebsd.dk> References: <24201.1138140983@critter.freebsd.dk>
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On Tuesday 24 January 2006 17:16, Poul-Henning Kamp wrote: > In message <200601241709.03450.jhb@freebsd.org>, John Baldwin writes: > >On Tuesday 24 January 2006 16:10, Poul-Henning Kamp wrote: > >> Here is a new version of my cpu accounting change patch. > > > >The XXX in calcru1() you can remove. The rux you are adding the current > > time to is a local rusage_ext on the stack. > > I found that out myself and forgot to remove the XXX :-) > > >However, your changes probably make > >it bogus in that the current code assumes it can subtract the start time > > of another CPU (for a thread running on another CPU) from the current > > time on this CPU to get the amount of time the other thread has been > > running on the other CPU since it last updated p->p_rux.rux_runtime. > > This is when we call calcru on a running process ? > > Yeah, that's a problem. Yeah, SIGINFO is an example, and getrusage() of another process might run into this, too. > I'd tend to say we should just forget about accounting for the > current quantum in that case. It was added to fix some of the "time going backwards" and "negative uptime" stuff I think. Ask Bruce. > This is a valid handling IMO because the result can never be used > in any final or definitive kind of way anyway. When the process > finishes or deschedules the numbers will get updated correctly. Unfortunately calcru() updates the millisecond counts (uu, su, iu) for running processes and I think having a bogus runtime gets that very confused. > Doing this may also simplify the locking of calcru ? Nah, it already runs lockless in some cases I think. > >Other than that this patch looks fine to me. FYI, Alpha also has a > > per-cpu counter (RPCC) that is used for the timecounter on UP Alphas. > > My Alpha is hosed right now and doesn't want to boot 6.0-R. I havn't had > time to boot my 5.0-R on it and do the upgrade to -current the long way. Heh, I have one running head atm. However, it's second CPU is having issues (I think the CPU fan has died) so it's less useful than in the past. :( -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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