DragonFly BSD
DragonFly kernel List (threaded) for 2004-02
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Re: lkwt in DragonFly

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Mon, 9 Feb 2004 00:50:20 -0800 (PST)

:Your explanation is interesting, I am sorry that I am new to DFly,
:but if two threads on same CPU wants to exclusivly access a data 
:structure, what lock should be used ? does token still work ? on
:FreeBSD, one can use mutex, but token is holden by CPU on DFly not by 
:thread, so a thread really does not know if it already held the lock
:or not, although its CPU already hold the token.
:David Xu

    If you want something that stays valid through a switch or a blocking
    condition then you would need to use a lockmgr lock.  If you just
    need atomicy across a short period of time in which you know the
    thread will not block, or in a situation where the code does the 
    right thing if another piece of code operates on the same
    data structure while the first piece is blocked, then a token
    would be sufficient.

					Matthew Dillon 

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