Date: Thu, 30 Mar 1995 17:20:47 -0800 From: David Greenman <davidg@Root.COM> To: terry@cs.weber.edu (Terry Lambert) Cc: vernick@cs.sunysb.edu, freebsd-hackers@FreeBSD.org Subject: Re: help with splbio, splnet, spl... Message-ID: <199503310122.RAA00444@corbin.Root.COM> In-Reply-To: Your message of "Thu, 30 Mar 95 18:09:59 MST." <9503310110.AA29972@cs.weber.edu>
next in thread | previous in thread | raw e-mail | index | archive | help
>> >It's a tiered interrupt scheme. You can block all interrupts >> >at or below a specified priority while you are doing high >> >priority stuff so that it gets done in time. The "fast" >> >interrupts can't be blocked. >> >> It doesn't work this way in FreeBSD. It is not a tierd interrupt scheme. >> Each of the interrupt classes are independant and do NOT block the others. The >> only exception to this is tty and net are ored together if you are using SLIP >> or PPP (the reason should be obvious). > >This must be (relatively) new... If you consider 6 years old (when 386BSD was first being put together) as "new", well...I suppose. >Why isn't it tiered? Because it doesn't need to be. In fact, it is better if it isn't. >This conflicts with what you said about splclock() and splhigh() in >your previous post: > >] splhigh() and splclock() block all interrupts except "fast" interrupts. > > >Would it be more correct to say that it is partially tiered, with >the potential for multiple interrupt classes in a single tier not >interfering with each other? It would be more accurate to say that "fast" interrupts are a kludge and are escentially unblockable and don't fit into the spl* scheme at all. -DG
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199503310122.RAA00444>