Date: Thu, 22 Jun 2000 14:01:07 -0700 From: Greg Lehey <grog@lemis.com> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Nick Hibma <n_hibma@calcaphon.com>, freebsd-smp@FreeBSD.ORG Subject: Re: irunning, width in bits. Message-ID: <20000622140107.E845@sydney.worldwide.lemis.com> In-Reply-To: <200006211539.IAA94918@apollo.backplane.com> References: <Pine.BSF.4.20.0006210034060.34122-100000@localhost> <200006211539.IAA94918@apollo.backplane.com>
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On Wednesday, 21 June 2000 at 8:39:02 -0700, Matthew Dillon wrote: > (Moving this to freebsd-smp, Bcc'ing current) > >> What about shared interrupts? How are they going to be treated? With the >> spl leaving the arena it somehow looks feasible to run one interrupt >> source on two different threads if there are two pieces of hardware >> attached to the same interrupt line. >> >>> From what I understood from dfr, when switching away from an interrupt >> handler it is converted into a full thread. When the second piece of >> hardware fires an interrupt it could then run at the same time. > > This came up at the meeting and the conclusion was that shared > interrupts would run serially. That is, each 'bit' in the cpl > (spl*(), also represented by ipending, the vector table > dispatch, and so forth) would be treated as a single interrupt > thread. If there are N interrupts hanging off that IRQ, then > each of the N would be run serially from a single interrupt > thread. I think, however, that Nick's suggestion is a thing we should follow up on--*after* we have got the simple case working. Once we have the ability to block in interrupt context, I'm sure we'll find lots of applications for our new-found freedom, some of them good. But first we need to understand the environment. Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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