If a thread is holding mutex when doing cv_destroy, it might end up waiting a
thread in cv_wait. The waiter would wake up trying to aquire the same mutex
and cause deadlock.
We solve this by move the mutex_enter to the bottom of cv_wait, so that
the waiter will release the cv first, allowing cv_destroy to succeed and have
a chance to free the mutex.
This would create race condition on the cv_mutex. We use xchg to set and check
it to ensure we won't be harmed by the race. This would result in the cv_mutex
debugging becomes best-effort.
Also, the change reveals a race, which was unlikely before, where we call
mutex_destroy while test threads are still holding the mutex. We use
kthread_stop to make sure the threads are exit before mutex_destroy.
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Issue zfsonlinux/zfs#4166
Issue zfsonlinux/zfs#4106
The do_div() macro expects unsigned types and this is detected in
powerpc implementation of do_div().
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#516
Limit the maximum object size to 1/128 of total system memory for
the kmem cache tests. Large values can result in out of memory errors
for systems with less the 512M of memory. Additionally, use the
known number of objects per-slab for calculating the number of
objects to use for a test.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The misc_deregister() function was changed to a void return type.
Rather than add compatibility code to detect this change simply
ignore the return code on all kernels. It was only used to log
an informational error message of no real value.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Attempting to perform a vfs_rename() on Linux 4.2 and newer kernels
results in an EACCES error. Rather than attempting to add and
maintain more ugly compatibility code it's best to just retire
this interface. As a first step the SPLAT test is disabled for
Linux 4.2 and newer kernels.
vn_rename: Failed vn_rename /tmp/vn.tmp.1 -> /tmp/vn.tmp.2 (13)
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue zfsonlinux/zfs#3653
Add a new defclsyspri macro which can be used to request the default
Linux scheduler priority. Neither the minclsyspri or maxclsyspri map
to the default Linux kernel thread priority. This makes it awkward to
create taskqs which run with the same priority as the rest of the kernel
threads on the system which can lead to performance issues.
All SPL callers which previously used minclsyspri or maxclsyspri have
been changed to use defclsyspri. The vast majority of callers were
part of the test suite which won't have an external impact. The few
places where it could impact performance the change was from maxclsyspri
to defclsyspri. This makes it more likely the process will be scheduled
which may help performance.
To facilitate further performance analysis the spl_taskq_thread_priority
module option has been added. When disabled (0) all newly created kernel
threads will use the default kernel thread priority. When enabled (1)
the specified taskq priority will be used. By default this value is
enabled (1).
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Build products from an out of tree build should be written
relative to the build directory. Sources should be referred
to by their locations in the source directory.
This is accomplished by adding the 'src' and 'obj' variables
for the module Makefile.am, using relative paths to reference
source files, and by setting VPATH when source files are not
co-located with the Makefile. This enables the following:
$ mkdir build
$ cd build
$ ../configure
$ make -s
This change also has the advantage of resolving the following
warning which is generated by modern versions of automake.
Makefile.am:00: warning: source file 'xxx' is in a subdirectory,
Makefile.am:00: but option 'subdir-objects' is disabled
Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue zfsonlinux/zfs#1082
Setting the TASKQ_DYNAMIC flag will create a taskq with dynamic
semantics. Initially only a single worker thread will be created
to service tasks dispatched to the queue. As additional threads
are needed they will be dynamically spawned up to the max number
specified by 'nthreads'. When the threads are no longer needed,
because the taskq is empty, they will automatically terminate.
Due to the low cost of creating and destroying threads under Linux
by default new threads and spawned and terminated aggressively.
There are two modules options which can be tuned to adjust this
behavior if needed.
* spl_taskq_thread_sequential - The number of sequential tasks,
without interruption, which needed to be handled by a worker
thread before a new worker thread is spawned. Default 4.
* spl_taskq_thread_dynamic - Provides the ability to completely
disable the use of dynamic taskqs on the system. This is provided
for the purposes of debugging and troubleshooting. Default 1
(enabled).
This behavior is fundamentally consistent with the dynamic taskq
implementation found in both illumos and FreeBSD.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes#458
Under Illumos taskq_wait() returns when there are no more tasks
in the queue. This behavior differs from ZoL and FreeBSD where
taskq_wait() returns when all the tasks in the queue at the
beginning of the taskq_wait() call are complete. New tasks
added whilst taskq_wait() is running will be ignored.
This difference in semantics makes it possible that new subtle
issues could be introduced when porting changes from Illumos.
To avoid that possibility the taskq_wait() function is being
updated such that it blocks until the queue in empty.
The previous behavior remains available through the
taskq_wait_outstanding() interface. Note that this function
was previously called taskq_wait_all() but has been renamed
to avoid confusion.
Signed-off-by: Chris Dunlop <chris@onthe.net.au>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#455
Slightly increasing the size of a kmutex_t has caused us to exceed
the stack frame warning size in splat_taskq_test2_impl(). To address
this the tq_args have been moved to the heap.
cc1: warnings being treated as errors
spl-0.6.3/module/splat/splat-taskq.c:358:
error: the frame size of 1040 bytes is larger than 1024 bytes
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Issue #435
There are regions in the ZFS code where it is desirable to be able
to be set PF_FSTRANS while a specific mutex is held. The ZFS code
could be updated to set/clear this flag in all the correct places,
but this is undesirable for a few reasons.
1) It would require changes to a significant amount of the ZFS
code. This would complicate applying patches from upstream.
2) It would be easy to accidentally miss a critical region in
the initial patch or to have an future change introduce a
new one.
Both of these concerns can be addressed by adding a new mutex type
which is responsible for managing PF_FSTRANS, support for which was
added to the SPL in commit 9099312 - Merge branch 'kmem-rework'.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Issue #435
In the original implementation of the SPL wrappers were provided
for module initialization and cleanup. This was done to abstract
away any compatibility code which might be needed for the SPL.
As it turned out the only significant compatibility issue was that
the default pwd during module load differed under Illumos and Linux.
Since this is such as minor thing and the wrappers complicate the
code they are being retired.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue zfsonlinux/zfs#2985
This change is designed to improve the memory utilization of
slabs by more carefully setting their size. The way the code
currently works is problematic for slabs which contain large
objects (>1MB). This is due to slabs being unconditionally
rounded up to a power of two which may result in unused space
at the end of the slab.
The reason the existing code rounds up every slab is because it
assumes it will backed by the buddy allocator. Since the buddy
allocator can only performs power of two allocations this is
desirable because it avoids wasting any space. However, this
logic breaks down if slab is backed by vmalloc() which operates
at a page level granularity. In this case, the optimal thing to
do is calculate the minimum required slab size given certain
constraints (object size, alignment, objects/slab, etc).
Therefore, this patch reworks the spl_slab_size() function so
that it sizes KMC_KMEM slabs differently than KMC_VMEM slabs.
KMC_KMEM slabs are rounded up to the nearest power of two, and
KMC_VMEM slabs are allowed to be the minimum required size.
This change also reduces the default number of objects per slab.
This reduces how much memory a single cache object can pin, which
can result in significant memory saving for highly fragmented
caches. But depending on the workload it may result in slabs
being allocated and freed more frequently. In practice, this
has been shown to be a better default for most workloads.
Also the maximum slab size has been reduced to 4MB on 32-bit
systems. Due to the limited virtual address space it's critical
the we be as frugal as possible. A limit of 4M still lets us
reasonably comfortably allocate a limited number of 1MB objects.
Finally, the kmem:slab_small and kmem:slab_large SPLAT tests
were extended to provide better test coverage of various object
sizes and alignments. Caches are created with random parameters
and their basic functionality is verified by allocating several
slabs worth of objects.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This patch achieves the following goals:
1. It replaces the preprocessor kmem flag to gfp flag mapping with
proper translation logic. This eliminates the potential for
surprises that were previously possible where kmem flags were
mapped to gfp flags.
2. It maps vmem_alloc() allocations to kmem_alloc() for allocations
sized less than or equal to the newly-added spl_kmem_alloc_max
parameter. This ensures that small allocations will not contend
on a single global lock, large allocations can still be handled,
and potentially limited virtual address space will not be squandered.
This behavior is entirely different than under Illumos due to
different memory management strategies employed by the respective
kernels. However, this functionally provides the semantics required.
3. The --disable-debug-kmem, --enable-debug-kmem (default), and
--enable-debug-kmem-tracking allocators have been unified in to
a single spl_kmem_alloc_impl() allocation function. This was
done to simplify the code and make it more maintainable.
4. Improve portability by exposing an implementation of the memory
allocations functions that can be safely used in the same way
they are used on Illumos. Specifically, callers may safely
use KM_SLEEP in contexts which perform filesystem IO. This
allows us to eliminate an entire class of Linux specific changes
which were previously required to avoid deadlocking the system.
This change will be largely transparent to existing callers but there
are a few caveats:
1. Because the headers were refactored and extraneous includes removed
callers may find they need to explicitly add additional #includes.
In particular, kmem_cache.h must now be explicitly includes to
access the SPL's kmem cache implementation. This behavior is
different from Illumos but it was done to avoid always masking
the Linux slab functions when kmem.h is included.
2. Callers, like Lustre, which made assumptions about the definitions
of KM_SLEEP, KM_NOSLEEP, and KM_PUSHPAGE will need to be updated.
Other callers such as ZFS which did not will not require changes.
3. KM_PUSHPAGE is no longer overloaded to imply GFP_NOIO. It retains
its original meaning of allowing allocations to access reserved
memory. KM_PUSHPAGE callers can be converted back to KM_SLEEP.
4. The KM_NODEBUG flags has been retired and the default warning
threshold increased to 32k.
5. The kmem_virt() functions has been removed. For callers which
need to distinguish between a physical and virtual address use
is_vmalloc_addr().
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This change introduces no functional changes to the memory management
interfaces. It only restructures the existing codes by separating the
kmem, vmem, and kmem cache implementations in the separate source and
header files.
Splitting this functionality in to separate files required the addition
of spl_vmem_{init,fini}() and spl_kmem_cache_{initi,fini}() functions.
Additionally, several minor changes to the #include's were required to
accommodate the removal of extraneous header from kmem.h.
But again, while large this patch introduces no functional changes.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
When running the SPLAT tests on a kernel with CONFIG_DEBUG_OBJECTS=y
enabled the following warning is generated.
ODEBUG: object is on stack, but not annotated
WARNING: at lib/debugobjects.c:300 __debug_object_init+0x221/0x480()
This is caused by the test cases placing a debug object on the stack
rather than the heap. This isn't harmful since they are small objects
but to make CONFIG_DEBUG_OBJECTS=y happy the objects have been relocated
to the heap. This impacted taskq tests 1, 3, and 7.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#424
Don't include the compatibility code in linux/*_compat.h in the public
header sys/types.h. This causes problems when an external code base
includes the ZFS headers and has its own conflicting compatibility code.
Lustre, in particular, defined SHRINK_STOP for compatibility with
pre-3.12 kernels in a way that conflicted with the SPL's definition.
Because Lustre ZFS OSD includes ZFS headers it fails to build due to a
'"SHRINK_STOP" redefined' compiler warning. To avoid such conflicts
only include the compat headers from .c files or private headers.
Also, for consistency, include sys/*.h before linux/*.h then sort by
header name.
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#411
When the SPL was originally written Linux tracepoints were still
in their infancy. Therefore, an entire debugging subsystem was
added to facilite tracing which served us well for many years.
Now that Linux tracepoints have matured they provide all the
functionality of the previous tracing subsystem. Rather than
maintain parallel functionality it makes sense to fully adopt
tracepoints. Therefore, this patch retires the legacy debugging
infrastructure.
See zfsonlinux/zfs@bc9f413 for the tracepoint changes.
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#408
As long as we can fit a minimum of one object/slab there's no reason
to prevent the creation of the cache. This effectively pushes the
maximum object size up to 32MB. The splat cache tests were extended
accordingly to verify this functionality.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The new shrinker API as of Linux 3.12 modifies "struct shrinker" by
replacing the @shrink callback with the pair of @count_objects and
@scan_objects. It also requires the return value of @count_objects to
return the number of objects actually freed whereas the previous @shrink
callback returned the number of remaining freeable objects.
This patch adds support for the new @scan_objects return value semantics
and updates the splat shrinker test case appropriately.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes#403
This is optional functionality which may or may not be useful to
ZFS when using older kernels. It is never a hard requirement.
Therefore this functionality is being removed from the SPL and
a simpler slimmed down version will be added to ZFS.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Platforms such as Illumos and FreeBSD have historically provided
global variables which summerize the memory state of a system.
Linux on the otherhand doesn't expose any of this information
to kernel modules and uses entirely different mechanisms for
memory management.
In order to simplify the original ZFS port to Linux these global
variables were emulated by the SPL for the benefit of ZFS. As ZoL
has matured over the years it has moved steadily away from these
interfaces and now no longer depends on them at all.
Therefore, this patch completely removes the global variables
availrmem, minfree, desfree, lotsfree, needfree, swapfs_minfree,
and swapfs_reserve. This greatly simplifies the memory management
code and eliminates a common area of confusion.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The get_vmalloc_info() function was used to back the vmem_size()
function. This was always problematic and resulted in brittle
code because the kernel never provided a clean interface for
modules.
However, it turns out that the only caller of this function in
ZFS uses it to determine the total virtual address space size.
This can be determined easily without get_vmalloc_info() so
vmem_size() has been updated to take this approach which allows
us to shed the get_vmalloc_info() dependency.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
When the SPL was originally written it was designed to use the
device_create() and device_destroy() functions. Unfortunately,
these functions changed considerably over the years making them
difficult to rely on.
As it turns out a better choice would have been to use the
misc_register()/misc_deregister() functions. This interface
for registering character devices has remained stable, is simple,
and provides everything we need.
Therefore the code has been reworked to use this interface. The
higher level ZFS code has always depended on these same interfaces
so this is also as a step towards minimizing our kernel dependencies.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
For consistency throughout the code update the SPLAT infrastructure
to use the wrapped mutex interfaces.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Apply the license specified in the META file to ensure the
compatibility checks are all performed consistently.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
While running SPLAT on a kernel with CONFIG_DEBUG_ATOMIC_SLEEP
enabled the taskq:front was flagged as a test which might sleep
which in an unsafe context. Specifically, the splat_vprint()
function which internally takes a mutex was being called under
a spin lock. Moving the log function outside the spin lock
cleanly solves this issue.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
For small objects the Linux slab allocator has several advantages
over its counterpart in the SPL. These include:
1) It is more memory-efficient and packs objects more tightly.
2) It is continually tuned to maximize performance.
Therefore it makes sense to layer the SPLs slab allocator on top
of the Linux slab allocator. This allows us to leverage the
advantages above while preserving the Illumos semantics we depend
on. However, there are some things we need to be careful of:
1) The Linux slab allocator was never designed to work well with
large objects. Because the SPL slab must still handle this use
case a cut off limit was added to transition from Linux slab
backed objects to kmem or vmem backed slabs.
spl_kmem_cache_slab_limit - Objects less than or equal to this
size in bytes will be backed by the Linux slab. By default
this value is zero which disables the Linux slab functionality.
Reasonable values for this cut off limit are in the range of
4096-16386 bytes.
spl_kmem_cache_kmem_limit - Objects less than or equal to this
size in bytes will be backed by a kmem slab. Objects over this
size will be vmem backed instead. This value defaults to
1/8 a page, or 512 bytes on an x86_64 architecture.
2) Be aware that using the Linux slab may inadvertently introduce
new deadlocks. Care has been taken previously to ensure that
all allocations which occur in the write path use GFP_NOIO.
However, there may be internal allocations performed in the
Linux slab which do not honor these flags. If this is the case
a deadlock may occur.
The path forward is definitely to start relying on the Linux slab.
But for that to happen we need to start building confidence that
there aren't any unexpected surprises lurking for us. And ideally
need to move completely away from using the SPLs slab for large
memory allocations. This patch is a first step.
NOTES:
1) The KMC_NOMAGAZINE flag was leveraged to support the Linux slab
backed caches but it is not supported for kmem/vmem backed caches.
2) Regardless of the spl_kmem_cache_*_limit settings a cache may
be explicitly set to a given type by passed the KMC_KMEM,
KMC_VMEM, or KMC_SLAB flags during cache creation.
3) The constructors, destructors, and reclaim callbacks are all
functional and will be called regardless of the cache type.
4) KMC_SLAB caches will not appear in /proc/spl/kmem/slab due to
the issues involved in presenting correct object accounting.
Instead they will appear in /proc/slabinfo under the same names.
5) Several kmem SPLAT tests needed to be fixed because they relied
incorrectly on internal kmem slab accounting. With the updated
test cases all the SPLAT tests pass as expected.
6) An autoconf test was added to ensure that the __GFP_COMP flag
was correctly added to the default flags used when allocating
a slab. This is required to ensure all pages in higher order
slabs are properly refcounted, see ae16ed9.
7) When using the SLUB allocator there is no need to attempt to
set the __GFP_COMP flag. This has been the default behavior
for the SLUB since Linux 2.6.25.
8) When using the SLUB it may be desirable to set the slub_nomerge
kernel parameter to prevent caches from being merged.
Original-patch-by: DHE <git@dehacked.net>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: DHE <git@dehacked.net>
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Closes#356
When comparing times gotten from ddi_get_lbolt, we have to take account of
wrap around of jiffies. Therefore, we cannot use 't1 < t2'. Instead we should
use 't1 - t2 < 0'.
This patch add ddi_time_after and friends to address this issue. They have
strict type restriction, clock_t for vanilla and int64_t for 64 version, to
prevent type conversion from screwing things.
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#335
Provide spl_kthread_create() as a wrapper to the kernel's kthread_create()
to provide pre-3.13 semantics. Re-try if the call is interrupted or if it
would have returned -ENOMEM. Otherwise return NULL.
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#339
Due to certain assumptions made in the the cred:groupmember test it
could result in false positives when run on specific distributions.
This was solely a bug in the test case and not in the groupmember()
function which the test case was validating.
To prevent future false positives the test case has been rewritten
to be both more rigerous and to make fewer assumptions about the
system.
Minor style cleanup was done to cr_groups_search() and groupmember()
functions.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
By setting __GFP_NORETRY the kernel memory reclaim logic was allowed to
abort early and dump a falled allocation stack to the console. Since
this was done in a tight loop to fill memory it could result in a large
number of stacks being dumped to the console. This in turn slowed down
the test sufficiently so it exceeded the time limit and failed.
To resolve this issue the __GFP_NORETRY flag is being removed. This is
how it should have been called originally to ensure we're simulating
the behavior of most callers which will use the GFP_KERNEL flag.
In addition, the reclaim granularity of 1000 objects was far to coarse
for this to be a realistic test. For kmem:slab_reclaim there might
only be a few thousand objects total in the cache. Therefore, the
SPLAT_KMEM_OBJ_RECLAIM constant for these tests was lowered. This
will cause the reclaim callback to run more frequently which makes
for a better test case.
The frequency of the cache reaping in kmem:slab_reap was increased
to accommodate the reduced number of objects released during the
reclaim.
These changes only impact the test cases and were done to remove
false positives caused by the test case itself.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Use the standard Linux MODULE_VERSION macro to expose the installed
spl and splat module versions. This will also automatically add a
checksum of the .c files and headers in "srcversion". See:
/sys/module/spl/version
/sys/module/spl/srcversion
/sys/module/splat/version
/sys/module/splat/srcversion
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closeszfsonlinux/zfs#1923
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
current_kernel_time() is used by the SPLAT, but it is not meant for
performance measurement. We modify the SPLAT to use getnstimeofday(),
which is equivalent to the gethrestime() function on Solaris.
Additionally, we update gethrestime() to invoke getnstimeofday().
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#279
Because spl_slab_size() was always returning -ENOSPC for caches of
type KMC_OFFSLAB the cache could never be created. Additionally
the slab size is rounded up to a page which is what kv_alloc()
expects. The kv_alloc() code will minimally allocate a page,
in the KMC_OFFSLAB case this could be reduced.
The basic regression tests kmem:slab_small, kmem:slab_large,
and kmem:slab_align regression were updated to test KMC_OFFSLAB.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ying Zhu <casualfisher@gmail.com>
Closes#266
Linux kernel commit torvalds/linux@0d01ff2 changes some
includes we were depending on through linux/proc_fs.h.
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #257
Update links to refer to the official ZFS on Linux website instead of
@behlendorf's personal fork on github.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Cache aging was implemented because it was part of the default Solaris
kmem_cache behavior. The idea is that per-cpu objects which haven't been
accessed in several seconds should be returned to the cache. On the other
hand Linux slabs never move objects back to the slabs unless there is
memory pressure on the system.
This behavior is now configurable through the 'spl_kmem_cache_expire'
module option. The value is a bit mask with the following meaning.
0x1 - Solaris style cache aging eviction is enabled.
0x2 - Linux style low memory eviction is enabled.
Both methods may be safely enabled simultaneously, but by default
both are disabled. It has never been clear if the kmem cache aging
(which has been around from day one) actually does any good. It has
however been the source of numerous bugs so I wouldn't mind retiring
it entirely.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes zfsonlinux/zfs#1227
Closes#210
As of Linux 3.4 the UMH_WAIT_* constants were renumbered. In
particular, the meaning of "1" changed from UMH_WAIT_PROC (wait for
process to complete), to UMH_WAIT_EXEC (wait for the exec, but not the
process). A number of call sites used the number 1 instead of the
constant name, so the behavior was not as expected on kernels with
this change.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The slightly increased size of the taskq_ent_t when debugging is
enabled has pushed the taskq:front splat test over frame size
limit. To resolve this dynamically allocate the taskq_ent_t
structures so they are part of the heap instead of the stack.
In function 'splat_taskq_test6_impl'
error: the frame size of 1648 bytes is larger than 1024 bytes
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The slightly increased size of the taskq_ent_t when debugging is
enabled has pushed the taskq:order splat test over frame size
limit. To resolve this dynamically allocate the taskq_ent_t
structures so they are part of the heap instead of the stack.
In function 'splat_taskq_test5_impl'
error: the frame size of 1680 bytes is larger than 1024 bytes
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Add a test case for taskq_cancel_id() to verify it is working
properly. Just like taskq:delay we start by dispatching 100
tasks. However this time 1/3 of the tasks use taskq_dispatch()
and will be run immediately, and 2/3 use taskq_dispatch_delay().
The idea is to create a busy taskq with both active, pending,
and delayed tasks.
After all the items have been successfully dispatched the test
begins randomly canceling known task ids. It will do this for
5 seconds randomly canceling a task id and then sleeping for a
few milliseconds. The task being canceled may have already run,
still be on the pending list, or may be currently being executed
by a worker thread. The idea is to ensure we catch any subtle
race conditions.
Once all the non-canceled tasks have completed we cross check
the number of tasks which ran with the number of tasks which
were successfully canceled. Additionally, we verify that the
taskq_cancel_id() function never blocks longer than needed.
This time is bounded by the longest run time of the task which
was dispatched.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Add a test case for taskq_dispatch_delay() to verify it is working
properly. The test dispatchs 100 tasks to a taskq with random
expiration times spread over 5 seconds. As each task expires and
gets executed by a worker thread it verifies that it was run at
the correct time. Once all the delayed tasks have been executed
we double check that all the dispatched tasks were successful.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Add the ability to dispatch a delayed task to a taskq. The desired
behavior is for the task to be queued but not executed by a worker
thread until the expiration time is reached. To achieve this two
new functions were added.
* taskq_dispatch_delay() -
This function behaves exactly like taskq_dispatch() however it
takes a third 'expire_time' argument. The caller should pass the
desired time the task should be executed as an absolute value in
jiffies. The task is guarenteed not to run before this time, it
may run slightly latter if all the worker threads are busy.
* taskq_cancel_id() -
Given a task id attempt to cancel the task before it gets executed.
This is primarily useful for canceling delay tasks but can be used for
canceling any previously dispatched task. There are three possible
return values.
0 - The task was found and canceled before it was executed.
ENOENT - The task was not found, either it was already run or an
invalid task id was supplied by the caller.
EBUSY - The task is currently executing any may not be canceled.
This function will block until the task has been completed.
* taskq_wait_all() -
The taskq_wait_id() function was renamed taskq_wait_all() to more
clearly reflect its actual behavior. It is only curreny used by
the splat taskq regression tests.
* taskq_wait_id() -
Historically, the only difference between this function and
taskq_wait() was that you passed the task id. In both functions you
would block until ALL lower task ids which executed. This was
semantically correct but could be very slow particularly if there
were delay tasks submitted.
To better accomidate the delay tasks this function was reimplemnted.
It will now only block until the passed task id has been completed.
This is actually a fairly low risk change for a few reasons.
* Only new ZFS callers will make use of the new interfaces and
very little common code was changed to support the new functions.
* The existing taskq_wait() implementation was not changed just
slightly refactored.
* The newly optimized taskq_wait_id() implementation was never
used by ZFS we can't accidentally introduce a new bug there.
NOTE: This functionality does not exist in the Illumos taskqs.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ensure the test thread blocks until the shrinker has completed its
work. This is done by putting the test thread to sleep and waking
it each time the shrinker callback runs. Once the shrinker size
drops to zero or we time out the test is allowed to proceed.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#96Closes#125Closes#182
The taskq:front test has a race condition where task 4 and 8
race to complete, due to an incorrectly calculated set of delay
"factors" (T). If task 4 wins and actually finishes first, the
verification of the order of completion will fail.
The delays calculated to order task completion do not take into
account the terminal line in the table, and so are all off by
a factor of 1. This causes all the tasks in all queues to finish
sooner than expected and the accumulated error is the root cause
of tasks 4 and 8 racing to complete first. Before the change the
"actual" table looks like I commented in #130.
I changed:
* the table in the comment to correctly reflect the test and the
factor timings needed.
* the individual task delay factors of T so that ONLY 1 task will
every 2T. (on average)
* 1T was reduced from 100ms to 50ms. This halves the duration of
the test and makes any remaining raciness more likely to cause
failures, but it did not cause the test to fail.
* simplified the delay factor logic by using a table look-up
instead of a switch.
* Added a "task started" message so that with -v it is possible
to see the order tasks are started.
* Moved the "task completed" message inside the spinlock so that
with -v the message truly reflects the absolute order of
completion as guaranteed by the spinlock.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#130
The preferred kernel interface for creating threads has been
kthread_create() for a long time now. However, several of the
SPLAT tests still use the legacy kernel_thread() function which
has finally been dropped (mostly).
Update the condvar and rwlock SPLAT tests to use the modern
interface. Frankly this is something we should have done a
long time ago.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#194
Disable this test because it may result in an OOM event on the
system which can result in the test infrastructure being killed.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The Fedora 3.6 debug kernel identified the following issue where
we create a thread under a spin lock. This isn't safe because
sleeping could result in a deadlock. Therefore the lock is changed
to a mutex so it's safe to sleep.
BUG: sleeping function called from invalid context at mm/slub.c:930
in_atomic(): 1, irqs_disabled(): 0, pid: 10583, name: splat
1 lock held by splat/10583:
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Chunwei Chen
Brian Behlendorf
Turbo Fredriksson
Chris Dunlop
Ned Bass
Tim Chase
Richard Yao
Yuxuan Shui
Steven Johnson