 |
» |
|
|
|
|  | |
The kernel maintains an MP data structure (typedef struct mpinfo)
that is an array containing system-global per-processor information
indexed by SPU number (the hard physical address (HPA)
of each processor). The structure and its components are documented
in the mp.h header file. The kernel variable mpproc_info
points to the start of the structure. The kernel variable mpproc_info[nmpinfo] points
to the end of the array. The general content of each mpinfo
entry is shown in the table that follows. Table 1-1 MP
information accessed through mpinfo_t | MP information | Purpose |
|---|
spinlock information | Number of spinlocks held,
spl level at
first spinlock taken, pointer to list of spinlocks currently held,
current critical spinlock, data on time spent spinning. | Interrupt vector
data | Pointer to interrupt vector address
(IVA), locations
of base and top of interrupt stack, pointer to interrupt status
word, deferred interrupts. | per-processor
counters and statistics | Array containing: Numbers of actual reads and writes to file-system
blocks, NFS reads and writes, bytes read via NFS, physical reads
and writes issued. Number of times run queue was occupied since bootup;
numbers of execs,
read/readv(),
write/writev(),
filename lookups, inode
fetches, select() calls,
System V semaphore and message operations, mux
I/O transfers, raw characters read, characters output since bootup. Numbers of active process, thread, inode,
and file entries allocated by the SPU.
| coprocessor
information | Two 8-bit masks, positioned
0-7; bit 7 corresponds to GR 31. Both elements are 0xC0
if floating point coprocessor is present. ccr_present
-to indicate the presence of coprocessor(s). ccr_enable
- indicates coprocessor(s) has passed self-test.
| Threads information | Current process priority,
indication of whether thread is on the processor, pointer to active
thread structure, space ID of thread's uarea,
setting for thread / SPU preemption. | Model information | Hardware version (CPU type
and speed) and ID, software version, ID, and capability, boot ID,
architectural revision, potential and current keys. architecture
revision (arch_rev)
identifies PA-RISC level of the CPU: | Time of day
information | Values for normalization
and synchronization of interval timer. | Powerfail information | Powerfail state, interval
timer ticks remaining, and exit state | Run queue information struct mp_rq | Includes index into an array
of run queue pointers (bestq),
average run-queue length (neavg_on_rq)
for load balancing, active locked and unlocked run queues by SPU
and type of lock, interval timing and run-queue spinlock pointers. | CPU status | The current state of a processor handling
a process is represented by one of the following values: MPBLOCK
waiting on kernel spinlock MPUSER executing
in user mode MPSYS
executing in system mode MPSWAIT
waiting on a kernel semaphore
|
Per-Processor Counters and Statistics | |
The statistics tracked through the mpcntrs
structure can be beneficial in comparing the activities of different
processors. From this you may be able to determine which processor
is handling the majority of NFS traffic or other specific filesystem
type activity. Perhaps the most interesting counters in this structure are
the counts for active processes, threads, inodes,
and files. Table 1-2 Counters
tracked in struct mpcntrs | Counter | Purpose |
|---|
activeprocs | Count of the number of processes
created by the SPU (number of proc table entries). This count in
incremented in allocproc() and
decremented in freeproc(). | activethreads | Count of number of threads
created by the SPU (number of thread table entries). This count
is incremented in allocthread()
and decremented in freethread(). | activeinodes | Count of how many inodes
have been allocated by the SPU (number of inode
table entries). The count is incremented whenever an inode is removed
from the free list by routines such as ieget(),
and vx_inoalloc(). | activefiles | Count of the number of file table entries
allocated by the SPU. The count is incremented in falloc() and
decrement whenever a filetable entry is freed by a call to FPENTRYFREE(). |
These counters track the number of active (in-use) entries
for each of the respective kernel tables. These counters must be
summed across all running processors to obtain the total number
of active entries for each table. The decision as to which processor's
mpinfo structure
to increment or decrement is based on identification of the current
processor. If a process is created on SPU A but later terminates
while running on SPU B, the activeprocs
counter will be incremented on SPU A but decremented on SPU B. |
![[Scope of information in MP data structures]](img/gfx3.gif)