Reduce kernel stack usage by lzjb_compress() by moving uint16 array
off the stack and on to the heap. The exact performance implications
of this I have not measured but we absolutely need to keep stack
usage to a minimum. If/when this becomes and issue we optimize.
Move xiou stat structures from a header to the dmu.c source as is
done with all the other kstat interfaces. This information is local
to dmu.c registered the xuio kstat and should stay that way.
If your only going to allow one allocator to be used and it is defined
at compile time there is no point including the others in the build.
This patch could/should be refined for Linux to make the metaslab
configurable at run time. That might be a bit tricky however since
you would need to quiese all IO. Short of that making it configurable
as a module load option would be a reasonable compromise.
In the linux kernel 'current' is defined to mean the current process
and can never be used as a local variable in a function. Simply
replace all usage of 'current' with 'curr' in this function.
This is a portability change which removes the dependence of the Solaris
thread library. All locations where Solaris thread API was used before
have been replaced with equivilant Solaris kernel style thread calls.
In user space the kernel style threading API is implemented in term of
the portable pthreads library. This includes all threads, mutexs,
condition variables, reader/writer locks, and taskqs.
Updated fix to detect if we are in an interrupt and only sleep if it
is safe to do some. I guess it must be safe to sleep under Solaris
this must be handled in a sort interrupt handler there
The DMU API has been modified to remove the dmu_objset_open, and
dmu_objset_close functions. Now you must explicitly *_create an
objset, then *_own it, *_disown it when not in use, and *_destroy
it when your through. All and all I like the API much better.
Additionally, while I was here I moved the zpios_cmd_t off the
stack because previous analysis showed it was very stack heavy.
Almost exclusively this patch handled the addition of another char
array to the zfs_cmd_t structure. Unfortunately c90 doesn't allow
zero filling the entire struct with the '= { 0 };' shorthand.
Originally these changes were on other gcc-* topic branches but
because c90 touches the same bit of code and I'd like to keep all
the gcc-* branches completely parallel I've moved these few bits
over here. This is one of the downsides of not just having one
big patch stack.
Fix new instances or changes in gcc flagged unused code. These are
mostly related to variables which are not used when debugging is
disabled and the ASSERTs are compiled out.
Brian Behlendorf