Date: Tue, 19 Jan 2010 11:44:08 +0100
From: Bernard van Gastel <bvgastel@bitpowder.com>
To: freebsd-hackers@freebsd.org
Subject: pthread_{mutex,cond} & fifo/starvation/scheduling policy
Message-ID: <71A129DC-68A0-46C3-956D-C8AFF1BA29E1@bitpowder.com>
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Hi everyone,
I'm curious to the exact scheduling policy of POSIX threads in relation =
to mutexes and conditions. If there are two threads (a & b), both with =
the following code:
while (1) {
pthread_mutex_lock(mutex);
...
pthread_mutex_unlock(mutex);
}
What is the scheduling policy of the different thread libraries? Are =
both threads getting an equal amount of time? Are there no starvation =
issues (are they executed in alternating turns)? (a test program of mine =
indicates that libpthread and libthr both have starvation issues, in =
contrary to Mac OS X 10.6)
Also, I'm interested in the scheduling behaviour in combination with =
pthread_cond. Get a signalled thread priority to relock the mutex it is =
waiting on, or is the relock operation just a normal lock operation and =
is handled as such? (so different kind of starvation issues can occur in =
the latter case)
I have googled extensively and browsed the libthr sources, but can't =
find the specs that I'm looking for. Any help will appreciated.
With regards,
Bernard van Gastel=
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