On Mon, Jul 09, 2007 at 11:14:18PM -0700, Alexander Kolbasov wrote:
> Hi Brendan,
>
> can I summarize your point as a proposal to extend kstat framework
> instead of providing filesystem-based representation for CPU-related
> information?
Yes, as a suggestion moving to a prototype. If this approach fails for
some reason, then move to /CPUfs or even /kstatfs etc.
I have nothing against statistic filesystems (I suggested a /connfs in my
talk at CEC2006 :), so long as it can be shown that the existing
infrastructure is inadequate and can't be fixed.
I've spent about 15 minutes typing it what such a kstat based CPU info
implementation may look like for an example system, attached below. If
someone can show how this would fail for a particular CPU type, that
would be good to know (and even better if they could suggest a fix :).
Naturally I'm eager to see such stable information available, somehow,
as I can imagine the sort of tools that this would make possible.
cheers,
Brendan
--
Brendan
[CA, USA]
kstat example
-------------
Our fictitious system has 2 sockets, each socket having 8 cores, each core
having 4 hardware threads. The L1 cache is shared between pairs of
cores, the L2 cache is shared across all cores on a single socket, and the
L3 cache is shared across both sockets.
CPU layout with kstat names,
+-- socket0
| |
| +--- core0
| | |
| | +--- thread0
| | |
| | +--- thread1
| | |
| | +--- thread2
| | |
| | +--- thread3
| |
| +--- core1
| | |
| | +--- thread4
| | ...
| |
| +--- core2
| | |
| | +--- thread8
| | ...
| |
| +--- core3
| |
| +--- thread12
| ...
|
+-- socket1
| |
| +--- core4
| | |
| | +--- thread32
| | |
... ... ...
Cache layout with kstat names,
+-- l1cache_0
|
+-- l1cache_1
|
+-- l1cache_2
|
+-- l1cache_3
...
+-- l2cache_0
|
+-- l2cache_1
+-- l3cache_0
kstat cpu_info module classes,
Class | Name | Desc
------------+-----------+---------------------
misc | cpu_info# | virtual CPU info (sockets or cores or threads,
| | depending on architecture)
socket | socket# | socket info
core | core# | core info (if they exist)
thread | thread# | thread info (if they exist)
l1cache | l1cache# | L1 cache info
l2cache | l2cache# | L2 cache info
l3cache | l3cache# | L3 cache info (if they exist)
Identifying relationships,
Relationship | How To
---------------------+------------
cores to sockets | core stats have the socket_id
threads to cores | thread stats have the core_id
threads to sockets | threads stats have the socket_id
L1 caches to cores | core stats have l1cache_id
L2 caches to cores | core stats have l2cache_id
L3 caches to cores | core stats have l3cache_id
who shares L1 caches | cpu_info stats with identical l1cache_ids
cpus to psets | cpu_info stats have pset_id
etc...
Identifier tree,
socket
^ ^ l1cache l2cache l3cache
|| | ^ ^ ^
| | | | / /
| | core | / /
| | ^ ^ | / /
| | | | | / /
| thread | | / /
| ^ / | / /
| | / / / /
cpu_info ----------
Either socket, core or thread can also identify the caches, depending on
who is the addressable unit of CPU that the system uses.
Example (fictional) kstat output, interesting lines prefixed with '!',
$ kstat -m cpu_info
module: cpu_info instance: 0
name: cpu_info0 class: misc
brand AMD Galactic(tm) Processor 2000
clock_MHz 6842
clog_id 0
! core_id 0
cpu_type i386
crtime 62.321739839
family 15
fpu_type i387 compatible
implementation x86 (AuthenticAMD ...
! l1cache_id 0
! l2cache_id 0
! l3cache_id 0
model 37
! pset_id 0
snaptime 5444553.88212403
! socket_id 0
state on-line
state_begin 1178664366
stepping 1
! type thread
! thread_id 0
vendor_id AuthenticAMD
[cpu_info0 ... cpu_info63]
module: cpu_info instance: 0
name: socket0 class: socket
brand AMD Galactic(tm) Processor 2000
clock_MHz 6842
cpu_type i386
crtime 62.321739839
! ncores 8
! nthreads 32
snaptime 5441324.10476323
! socket_id 0
state on-line
state_begin 1178664366
module: cpu_info instance: 0
name: socket1 class: socket
brand AMD Galactic(tm) Processor 2000
clock_MHz 6842
cpu_type i386
crtime 62.321739839
! ncores 8
! nthreads 32
snaptime 5441324.10476323
! socket_id 1
state on-line
state_begin 1178664366
module: cpu_info instance: 0
name: core0 class: core
clock_MHz 6842
! core_id 0
! l1cache_id 0
! l2cache_id 0
! l3cache_id 0
! nthreads 4
snaptime 11214398.1110444
state on-line
! socket_id 0
state_begin 1172889991
module: cpu_info instance: 0
name: core1 class: core
clock_MHz 6842
! core_id 1
! l1cache_id 0
! l2cache_id 0
! l3cache_id 0
! nthreads 4
snaptime 11214398.1110444
state on-line
! socket_id 0
state_begin 1172889991
module: cpu_info instance: 0
name: core2 class: core
clock_MHz 6842
! core_id 2
! l1cache_id 1
! l2cache_id 0
! l3cache_id 0
! nthreads 4
snaptime 11214398.1110444
state on-line
! socket_id 0
state_begin 1172889991
[core3 ... core7]
module: cpu_info instance: 0
name: core8 class: core
clock_MHz 6842
! core_id 8
! l1cache_id 1
! l2cache_id 4
! l3cache_id 0
! nthreads 4
snaptime 11214398.1110444
state on-line
! socket_id 1
state_begin 1172889991
module: cpu_info instance: 0
name: core9 class: core
clock_MHz 6842
! core_id 9
! l1cache_id 1
! l2cache_id 4
! l3cache_id 0
! nthreads 4
snaptime 11214398.1110444
state on-line
! socket_id 1
state_begin 1172889991
[core10 ... core15]
module: cpu_info instance: 0
name: thread0 class: thread
clock_MHz 6842
! core_id 0
snaptime 11214398.1110444
state on-line
! socket_id 0
state_begin 1172889991
! thread_id 0
[thread1 ... thread63]
module: cpu_info instance: 0
name: l1cache_0 class: l1cache
! l1cache_id 0
! ncores 2
! nthreads 8
! size 32768
snaptime 11214398.1110444
! socket_id 0
module: cpu_info instance: 0
name: l1cache_1 class: l1cache
! l1cache_id 1
! ncores 2
! nthreads 8
! size 32768
snaptime 11214398.1110444
! socket_id 0
[l1cache_2 .. l1cache_7]
module: cpu_info instance: 0
name: l2cache_0 class: l2cache
! l2cache_id 0
! ncores 8
! nthreads 32
! size 8388608
snaptime 11214398.1110444
! socket_id 0
module: cpu_info instance: 0
name: l2cache_1 class: l2cache
! l2cache_id 1
! ncores 8
! nthreads 32
! size 8388608
snaptime 11214398.1110444
! socket_id 1
module: cpu_info instance: 0
name: l3cache_0 class: l3cache
! l3cache_id 0
! ncores 16
! nsockets 2
! nthreads 64
! size 33554432
snaptime 11214398.1110444
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