Date: Mon, 12 Nov 2001 16:24:32 -0800 (PST)
From: John Baldwin <jhb@FreeBSD.org>
To: Julian Elischer <julian@elischer.org>
Cc: freebsd-arch@FreeBSD.org, Robert Watson <rwatson@FreeBSD.org>, Terry Lambert <tlambert2@mindspring.com>, Matthew Dillon <dillon@apollo.backplane.com>
Subject: Re: cur{thread/proc}, or not.
Message-ID: <XFMail.011112162432.jhb@FreeBSD.org>
In-Reply-To: <Pine.BSF.4.21.0111121608240.94926-100000@InterJet.elischer.org>
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On 13-Nov-01 Julian Elischer wrote: > > > On Mon, 12 Nov 2001, Matthew Dillon wrote: > >> You want to be very careful not to bloat the concept. We >> already have severe bloatage in the mutex code and that has >> led to a lot of unnecessary complexity. A huge amount, >> in fact. We have so many types of mutexes it makes my >> head spin and I'm not very happy about it. Forget about >> 'shared' verses 'exclusive'. A reference count is a >> reference count, that's all. If you keep the concept >> simple you can implement more functionality horizontally >> rather then implementing more complexity vertically. >> >> For example, consider this API for pool mutexes. > > [...] > > weren't you just complaining that there were too many kinds of mutex? > I'm not sure how this fits under "reference counting API" > > ANyhow can you explain the idea of a pool mutex more clearly? Heh, think of it as a pool of mutexes, not a different type of mutex. Instead of having 1 mutex for each object, you use a hash table of mutexes for a set of objects. Thus, if you have 50 objects vs. 500 objects, if you embed 1 mutex for each object, you bloat each object and have 500 locks instead of 50 locks. Using pool mutexes, you only have N number of mutexes regardless of the number of mutexes. Note that if pool mutexes are non-recursive, they can't be safely used when you might have more than one object of a given set locked at a time. For example, process locks are the only object we do this with currently. -- John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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