Date: Wed, 4 Jul 2001 09:38:17 -0700 (PDT) From: Matt Dillon <dillon@earth.backplane.com> To: freebsd-smp@freebsd.org Subject: VM Commits / GIANT_ macros Message-ID: <200107041638.f64GcH844850@earth.backplane.com>
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Hello everyone! Ok, after talking with John and others at USENIX
and a doing a couple of back and forths with Alfred, I am officially
taking over the main-line machine-independant VM system in -current.
I will also be working on i386 pmap, vm_object, vm_map, and the buffer
cache (in regards to mutexes & Giant).
Finally, I have begun instrumenting pieces of -current with GIANT_ macros
to formalize and assert Giant conditions. These macros will also allow
us to remove Giant via sysctl in a piecemeal fashion, so when someone
believes they have made a section giant-free, they can use the
GIANT_DEPRECIATED macro along with a sysctl to allow other developers
to conditionally turn Giant off there (e.g. so your systems don't crash
when you are just trying to boot or install a new kernel).
Basic documentation on the GIANT_ macros is available at:
http://apollo.backplane.com/FreeBSDSmp/
You do not have to lift a finger re: the GIANT_ macros if you do not
want to, but I will be instrumenting them throughout the codebase as
I go along. These macros only do stuff if INVARIANTS is turned on
(all -current developers should obviously have INVARIENTS turned on).
--
The VM mutex backout has been committed and tested w/ buildworld
on IA32/UP. I tried to cleanup the other platforms as well but
obviously couldn't test them. My next task is further instrumentation
and the implementation of fine-grained vm_page, vm_map, and vm_object
mutexes, and I will also use GIANT_DEPRECIATED to attempt to move certain
syscalls (not as many as Alfred tried to move) out from under Giant.
I expect this to take a number of man-days but since my time is mostly
limited to weekends and evenings this could translate to a month
or more in realtime.
-Matt
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