On Sat, Sep 5, 2009 at 12:09 AM, Yossi Lev (Sun Labs)<yosef....@sun.com> wrote: > >> Somebody will have to confirm, but I think global variables are >> lock-protected in DTrace, so you should be able to use one to store the >> sequence number. > > Actually, from messages that I saw in this forum, and my (little) > experience with dtrace, access to global variable is not MT-safe. I > definitely recall trying to increment a global counter to count the > number of calls to a function called by multiple threads, and seeing > lost updates. I also saw messages in this forum telling users to use > aggregations whenever an MT-safe counting is necessary, for both > scalability and safety reasons. So my understanding is that maintaining > a sequence number (that has to be incremented by each thread at the end > of each sequence) cannot be done using a global variable --- am I > missing something? >
No, that's correct. There is no protection for global variables in DTrace. Chad _______________________________________________ dtrace-discuss mailing list dtrace-discuss@opensolaris.org
