Both css_evaluate_new_subchannel and cio_validate_subchannel used
stsch and css_sch_is_valid to check for a valid device.
Reduce stsch calls during subchannel evaluation by re-using schib
data. Also the type/devno valid information is only checked once.
Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
In css_alloc_subchannel we allocate the subchannel and do a
validation of the subchannel (to decide if we should look for
devices via this subchannel). On a typical LPAR we find lots
of subchannels to be invalid (because there is no device
attached or the device is blacklisted) leading to lots of
useless kmalloc and kfree calls.
This patch changes the order to only allocate the subchannels
that have been found valid.
Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The css bus code uses 2 initcalls: channel_subsystem_init to
initialize internal data and channel_subsystem_init_sync to
start scanning for devices and wait for it to finish.
The start scanning for devices part is moved to the first
initcall such that more work happens in parallel.
Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Improve locking in chp_new to make sure that we don't register
the same chpid twice. Chpid registration was synchronized via
the machine check handler thread but we also have codepaths to
look for new chpids triggered independent of that thread (during
IPL or resume from hibernate).
Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Simplify error handling during css initialization by moving the error
handling code to setup_css (which now cleans up after itself).
Also remove the odd special cleanup handling of the pseudo_subchannel.
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Obtain the real channel subsystem id and use that for the generation
of a unique path group id. Note that this change does not affect the
channel subsystem id as used in the user-visible naming of subchannels
and friends.
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Dong Jia Shi <bjsdjshik@linux.vnet.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Currently the cssid in various structures is used as the id of
the respective channel subsystem. Sometimes however we call the
index in the channel_subsystems array cssid. In some places the
id is even used as the index.
Provide a new define MAX_CSS_IDX and use it where appropriate.
In addition to that provide a dummy function to find a channel
subsystem by its id and a macro to iterate over the channel
subsystems.
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The Makefile currently controlling compilation of this code is:
obj-y += airq.o blacklist.o chsc.o cio.o css.o chp.o idset.o isc.o \
fcx.o itcw.o crw.o ccwreq.o trace.o ioasm.o
ccw_device-objs += device.o device_fsm.o device_ops.o
ccw_device-objs += device_id.o device_pgid.o device_status.o
obj-y += ccw_device.o cmf.o
...meaning that the files here are not being built as modular.
Lets remove the couple traces of modular infrastructure use, so that
when reading the code there is no doubt it is builtin-only.
Since module_init translates to device_initcall in the non-modular
case, the init ordering remains unchanged with this commit.
Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.
We delete the MODULE_LICENSE tag etc. since all that information
was (or is now) contained at the top of the file in the comments.
We replace module.h with export.h where the file does export some
symbols.
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Arnd Bergmann <arndb@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
There is no longer a need to maintain two versions of the same inline
assembly - one with exception handling, and one without - so get rid of
the duplicates and adjust names accordingly. This applies to stsch_err
and msch_err which are now renamed to stsch and msch respectively,
while the original msch function is removed.
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Simplify the css_generate_pgid code by using stap() independent of
CONFIG_SMP. For !CONFIG_SMP builds stap() will deliver the address
of the cpu we IPL'ed from (which can be != 0).
Note: the ifdef was likely added to be compatible with _very_ old
machines which we don't support anyway.
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
During resume from hibernate we already reenable measurement block
updates on a per device basis. In addition to that we also need to
activate channel measurement globally using the set channel monitor
instruction.
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Subchannel looping function for_each_subchannel_staged() allocates a
subchannel-ID-bitmap to efficiently iterate over the list of known
and unknown subchannels. Since this function is also used to iterate
over known-subchannels only, optimize that case by not requiring the
ID-bitmap allocation and falling back to simple bus_for_each_dev()
looping.
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Reviewed-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The CIO layer scans for newly available I/O devices by performing a scan
of available subchannels using the Store Subchannel (STSCH) instruction.
Performing too many STSCH instructions in a tight loop can cause high
Hypervisor overhead which can negatively impact the performance of the
virtual machine as a whole.
A subchannel scan is triggered for example during a hardware event that
indicates that a channel path has become available. It is also triggered
by the DASD device driver for each device that is set online.
This patch reduces the number of STSCH instructions being performed by
delaying the start of the actual subchannel scan by 1 second. Multiple
scan requests that are scheduled during this time will be merged into a
single scan loop.
The trade-off consists of a short delay that is introduced between
the time that the event is processed and a newly available device
becoming usable. This delay should be acceptable since it only
affects devices that have not been in use before.
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Reviewed-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The CIO layer scans for newly available I/O devices by performing a scan
of available subchannels using the Store Subchannel (STSCH) instruction.
This processing can take a significant amount of time during which no
other task can run on the same CPU (unless CONFIG_PREEMPT has been
enabled). As a result, scheduling latencies for other tasks are
increased noticeably, especially on a single-CPU system.
Fix this problem by explicitly allowing other tasks to be scheduled
each time a subchannel has been processed.
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Reviewed-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Access to the slow_subchannel_set has to be secured via the
slow_subchannel_lock.
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The usage of strict_strtoul() is not preferred, because
strict_strtoul() is obsolete. Thus, kstrtoul() should be
used.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
cio_validate_subchannel is used to do some basic checks to find out
if it's worth to further investigate a subchannel. Move the allocation
and initialization of the subchannels locks to css_alloc_subchannel.
Clean up the functions involved while at it.
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Sebastian Ott
Joe Perches
Greg Kroah-Hartman
Sebastian Ott
Paul Gortmaker
Peter Oberparleiter
Pierre Morel
Jingoo Han