Date: Mon, 29 Nov 1999 12:22:35 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: "Daniel C. Sobral" <dcs@newsguy.com> Cc: freebsd-arch@freebsd.org Subject: Re: Threads and the scheduler Message-ID: <199911292022.MAA08694@apollo.backplane.com> References: <3842DBB5.8AFC9B6@newsguy.com>
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:I have a question.
:
:Our scheduler is based on the assumption that i/o bound processes
:will block, and cpu bound processes will not. Because of that, we
:can support a _lot_ of i/o bound processes on a 64 Hz scheduler. If,
:though, we allow the i/o bound processes to always make use of their
:full quanta through use of threads, won't this have a huge impact on
:our ability to support many i/o bound processes?
:
:So, I guess what I'm getting at is: won't the proposed thread model
:have an impact on the effectiveness of our scheduler?
:
:--
:Daniel C. Sobral (8-DCS)
No, it won't, because most context switches are synchronous and
the tick interval doesn't apply in those cases. Asynchronizing
I/O does not necessarily mean that the calling thread will continue to
run. If it has nothing to do it is going to exit or go to sleep whether
the I/O is asynchronous or not. It is definitely not going to waste
cpu finishing out its quanta.
-Matt
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