The s390_hypfs filesystem is deprecated and shouldn't be used due to its
rather odd semantics. It creates a whole directory structure with static
file contents so a user can read a consistent state while within that
directory.
Writing to its update attribute will remove and rebuild nearly the whole
filesystem, so that again a user can read a consistent state, even if
multiple files need to be read.
Given that this wastes a lot of CPU cycles, and involves a lot of code,
binary interfaces have been added quite a couple of years ago, which simply
pass the binary data to user space, and let user space decode the data.
This is the preferred and only way how the data should be retrieved.
The assumption is that there are no users of the s390_hypfs filesystem.
However instead of just removing the code, and having to revert in case
there are actually users, factor the filesystem code out and make it only
available via a new config option.
This config option is supposed to be disabled. If it turns out there are no
complaints the filesystem code can be removed probably in a couple of
years.
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This is an extension of the already existing hypfs for LPAR (DIAG 204).
Data returned by DIAG 2fc is exported using the s390_hypfs when Linux
is running under z/VM. Information about cpus and memory is provided.
Data is put into different virtual files which can be accessed from user
space. All values are represented as ASCII strings
Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Correct some comments in the hypervisor filesystem.
Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
On zSeries machines there exists an interface which allows the operating
system to retrieve LPAR hypervisor accounting data. For example, it is
possible to get usage data for physical and virtual cpus. In order to
provide this information to user space programs, I implemented a new
virtual Linux file system named 's390_hypfs' using the Linux 2.6 libfs
framework. The name 's390_hypfs' stands for 'S390 Hypervisor Filesystem'.
All the accounting information is put into different virtual files which
can be accessed from user space. All data is represented as ASCII strings.
When the file system is mounted the accounting information is retrieved and
a file system tree is created with the attribute files containing the cpu
information. The content of the files remains unchanged until a new update
is made. An update can be triggered from user space through writing
'something' into a special purpose update file.
We create the following directory structure:
<mount-point>/
update
cpus/
<cpu-id>
type
mgmtime
<cpu-id>
...
hyp/
type
systems/
<lpar-name>
cpus/
<cpu-id>
type
mgmtime
cputime
onlinetime
<cpu-id>
...
<lpar-name>
cpus/
...
- update: File to trigger update
- cpus/: Directory for all physical cpus
- cpus/<cpu-id>/: Directory for one physical cpu.
- cpus/<cpu-id>/type: Type name of physical zSeries cpu.
- cpus/<cpu-id>/mgmtime: Physical-LPAR-management time in microseconds.
- hyp/: Directory for hypervisor information
- hyp/type: Typ of hypervisor (currently only 'LPAR Hypervisor')
- systems/: Directory for all LPARs
- systems/<lpar-name>/: Directory for one LPAR.
- systems/<lpar-name>/cpus/<cpu-id>/: Directory for the virtual cpus
- systems/<lpar-name>/cpus/<cpu-id>/type: Typ of cpu.
- systems/<lpar-name>/cpus/<cpu-id>/mgmtime:
Accumulated number of microseconds during which a physical
CPU was assigned to the logical cpu and the cpu time was
consumed by the hypervisor and was not provided to
the LPAR (LPAR overhead).
- systems/<lpar-name>/cpus/<cpu-id>/cputime:
Accumulated number of microseconds during which a physical CPU
was assigned to the logical cpu and the cpu time was consumed
by the LPAR.
- systems/<lpar-name>/cpus/<cpu-id>/onlinetime:
Accumulated number of microseconds during which the logical CPU
has been online.
As mount point for the filesystem /sys/hypervisor/s390 is created.
The update process is triggered when writing 'something' into the
'update' file at the top level hypfs directory. You can do this e.g.
with 'echo 1 > update'. During the update the whole directory structure
is deleted and built up again.
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Ingo Oeser <ioe-lkml@rameria.de>
Cc: Joern Engel <joern@wohnheim.fh-wedel.de>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
