Date: Mon, 8 Apr 1996 15:10:32 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: hasty@rah.star-gate.com (Amancio Hasty Jr.) Cc: roell@blah.a.isar.de, hackers@FreeBSD.org, roell@xinside.com Subject: Re: The F_SETOWN problem.. Message-ID: <199604082210.PAA03116@phaeton.artisoft.com> In-Reply-To: <199604081853.LAA02584@rah.star-gate.com> from "Amancio Hasty Jr." at Apr 8, 96 11:53:43 am
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> Now if we had a mechanism like ast delivery in VMS you wouldn't be having > all this problems. 8) > > I often wonder why the kludgy asynch signal notification was not taken > a step further to implement full asynchronous i/o . > > Aside from that tty drivers would have to be split into two parts: > one to do the i/o at a high priority and the other half to process > the tty events. To avoid context switching as a result of anything other than involuntary timer-based preemption or vlountary call-based preemption, of course. Anything else results in you switching address spaces much to frequently, with the resulting high system overhead. Hence the joke: "An elephant is a mouse running VMS". If the events still queued to process quantum, that would be a different matter, but then what about user space reentry, specifically AST stacks when multiple AST's fire before a single AST can finish processing? Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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