Date: Wed, 22 Nov 2000 18:28:38 -0500 (EST) From: Daniel Eischen <eischen@vigrid.com> To: John Baldwin <jhb@FreeBSD.ORG> Cc: Terry Lambert <tlambert@primenet.com>, arch@FreeBSD.ORG, jlemon@flugsvamp.com, bright@wintelcom.net Subject: Re: Thread-specific data and KSEs Message-ID: <Pine.SUN.3.91.1001122182015.7920C-100000@pcnet1.pcnet.com> In-Reply-To: <XFMail.001122141324.jhb@FreeBSD.org>
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On Wed, 22 Nov 2000, John Baldwin wrote: > > On 22-Nov-00 Terry Lambert wrote: > > The %gs register already has to be saved for WINE processes, > > so it's taken (at least when USER_LDT is defined). So there > > would not be an additional context switch for it. > > Ok. Since %fs is only used in the kernel and is saved/restored it might be a > good thing to use instead. I didn't think %fs was saved, but if it is, that's fine with me too. > > I think that if you guys go forward with this, you should do an > > indirect through whatever you end up using. I realize this will > > cost an additional 6 clock cycles, but it will let you expand > > the list of things indefinitely, going forward, instead of having > > to keep a register dedicated for backward compatability, and then > > somehow "grow a new one" when you need to do something similar to > > this again, in the future. > > It will be an indirect if I have any say in it. :) Currently we use %fs in the > kernel to address a segment that contains per-CPU data. I think that if we use > a seg reg, then we should have it address a segment that contains per-KSE data. Didn't Terry want an additional level of indirection? If we have %fs address a segment containing per-KSE data, then I'd like to place pointers to both the KSE struct and the thread struct (2 slots) in this segment (this would remove 1 level of indirection to "current thread"). -- Dan Eischen To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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