Date: Tue, 22 Jun 2004 15:27:01 -0700 (PDT) From: Julian Elischer <julian@elischer.org> To: John Baldwin <jhb@FreeBSD.org> Cc: FreeBSD current users <current@FreeBSD.org> Subject: Re: ithread priority question... Message-ID: <Pine.BSF.4.21.0406221526000.54870-100000@InterJet.elischer.org> In-Reply-To: <200406221717.13179.jhb@FreeBSD.org>
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On Tue, 22 Jun 2004, John Baldwin wrote: > On Monday 21 June 2004 03:48 am, Julian Elischer wrote: > > On Mon, 21 Jun 2004, Bruce Evans wrote: > > > On Sun, 20 Jun 2004, Julian Elischer wrote: > > > > In swi_add, the priority is multiplied by PPQ. > > > > This is a layering violation really because PPQ should only be known > > > > within the scheduler.... but..... "Why multiply by PPQ inthe first > > > > place?" we are not using the system run queues for interrupt threads. > > > > > > > > (PPQ = Priorities Per Queue). > > > > > > > > Without this you can remove runq.h from proc.h and include it only in > > > > the scheduler related files. > > > > > > I agree that this makes no sense. Apart from the layering violation, > > > It seems to just waste priority space. The wastage is not just cosmetic > > > since someone increased the number of SWIs although there was no room > > > for expansion. > > > > > > > > > Hardware ithread priorities are also separated by 4. The magic number 4 > > > is encoded in their definitions in priority.h. It's not clear if the 4 > > > is PPQ or just room for expansion without changing the ABI. Preserving > > > this ABI doesn't seem very important. > > > > seems pointless to me.. > > It looks to me that at on stage someone was considerring using the > > standard run-queue code to make interrupt threads runnable. > > They wanted each interrupt thread to eb on a differen queue and to use > > the ffs() code to find the next one to run. > > That was the intention. One question though, if the ithreads aren't on the > system run queues then which run queues are they on? aren't they run from the interupt? > > -- > 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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