Date: Tue, 7 Aug 2001 13:08:08 -0400 From: Garance A Drosihn <drosih@rpi.edu> To: Matt Dillon <dillon@earth.backplane.com>, Terry Lambert <tlambert2@mindspring.com> Cc: Mike Smith <msmith@FreeBSD.ORG>, Zhihui Zhang <zzhang@cs.binghamton.edu>, freebsd-hackers@FreeBSD.ORG Subject: Re: Allocate a page at interrupt time Message-ID: <p05101002b795cefe0a64@[128.113.24.47]> In-Reply-To: <200108071655.f77Gt9M32808@earth.backplane.com> References: <200108070739.f777dmi08218@mass.dis.org> <3B6FB0AE.8D40EF5D@mindspring.com> <200108071655.f77Gt9M32808@earth.backplane.com>
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At 9:55 AM -0700 8/7/01, Matt Dillon wrote: >:> > It also has the unfortunate property of locking us into virtual >:> > wire mode, when in fact Microsoft demonstrated that wiring down >:> > interrupts to particular CPUs was good practice, in terms of >:> > assuring best performance. [...] >:> >:> Terry, this is *total* garbage. >:> >:> Just so you know, ok? >: >:What "this", exactly? >: >:That "virtual wire" mode is actually a bad idea for some >:applications -- specifically, high speed networking with >:multiple gigabit ethernet cards? > > All the cpu's don't get the interrupt, only one does. > >:That Microsoft demonstrated that wiring down interrupts >:to a particular CPU was a good idea, and kicked both Linux' >:and FreeBSD's butt in the test at ZD Labs? > > Well, if you happen to have four NICs and four CPUs, and > you are running them all full bore, I would say that > wiring the NICs to the CPUs would be a good idea. That > seems like a rather specialized situation, though. Okay, that's helpful to sort out the discussion. I'd agree that is a specialized situation, one which wouldn't be critical to many freebsd users. Is Terry right that the current strategy will "lock us into virtual wire mode", in some way which means that this specialized situation CANNOT be handled? (it would be fine if it were "handled" via some specialized kernel option, imo. I'm just wondering what the limitations are. I do not mean to imply we should follow some different strategy here, I'm just wondering...) -- Garance Alistair Drosehn = gad@eclipse.acs.rpi.edu Senior Systems Programmer or gad@freebsd.org Rensselaer Polytechnic Institute or drosih@rpi.edu To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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