Use the '.p' command on the slot of interest, and find the pTCB, which is the linear address of the Thread Control Block.
For slot F, below, we see the following FOR .p output:
*
Slot Pid Ppid Csid Ord Sta Pri pTSD pPTDA pTCB Disp SG Name
000c 0005 0000 0005 0001 blk 0200 7cf7f000 7d1858a4 7d16a0d8 1eb8 00 pgma
0008 0005 0000 0005 0002 blk 081f 7cf77000 7d1858a4 7d169a28 1ea8 00 pgma
000e 0005 0000 0005 0003 blk 021f 7cf83000 7d1858a4 7d16a430 1ea8 00 pgma
000f 0005 0000 0005 0004 blk 061f 7cf85000 7d1858a4 7d16a5dc 1ea8 00 pgma
0010 0005 0000 0005 0005 blk 0200 7cf87000 7d1858a4 7d16a788 00 pgma
000d 0006 0000 0006 0001 blk 0200 7cf81000 7d1860d0 7d16a284 1eb8 00 pgmb
000a 0006 0000 0006 0002 blk 021f 7cf7b000 7d1860d0 7d169d80 1eb8 00 pgmb
0013 0006 0000 0006 0003 blk 0800 7cf8d000 7d1860d0 7d16ac8c 1eb8 00 pgmb
DB %7D16A5DC+164 L 6 would show ( for slot f )
SEE CAUTION, BELOW
%7D16A740 02 1F xx xx 1F 06
class / / ------ the word value 061F
level / actually used by the dispatcher
CAUTION: the offset used is correct for WARP CONNECT, but the addresses are what were used in OS/2 2.11, so this is a somewhat mixed example. Any offset in any control block may change any time a fix or new version is installed. Please refer to the Thread Control Block in the System Diagnostic Reference for offsets relating to other versions.
The first byte is the programmer's priority class, ranging from 1 to 4.
The second byte is the level within the class, ranging from 00 to 1F. The
third and fourth bytes are not useful. The fifth and sixth bytes are OS/2's
computed dispatching priority. This field is a word, so the high order part
is byte 6.
081F is the highest possible value.
0100 is the lowest possible value.
On a uniprocessor, using DosSetPriority to make yourself time-critical at the highest delta value would give you an extremely good chance of not being pre-empted, and was occasionally misused for serialization. This will never work on a multiprocessor, and is risky even on a uniprocessor, because a page fault will cause you to lose control while the page is processed, just as doing I/O to a file will cause a thread to block if access to the actual device is required.