This patch amounts to a mostly complete rewrite of the k_mem_pool
allocator, which had been the source of historical complaints vs. the
one easily available in newlib. The basic design of the allocator is
unchanged (it's still a 4-way buddy allocator), but the implementation
has made different choices throughout. Major changes:
Space efficiency: The old implementation required ~2.66 bytes per
"smallest block" in overhead, plus 16 bytes per log4 "level" of the
allocation tree, plus a global tracking struct of 32 bytes and a very
surprising 12 byte overhead (in struct k_mem_block) per active
allocation on top of the returned data pointer. This new allocator
uses a simple bit array as the only per-block storage and places the
free list into the freed blocks themselves, requiring only ~1.33 bits
per smallest block, 12 bytes per level, 32 byte globally and only 4
bytes of per-allocation bookeeping. And it puts more of the generated
tree into BSS, slightly reducing binary sizes for non-trivial pool
sizes (even as the code size itself has increased a tiny bit).
IRQ safe: atomic operations on the store have been cut down to be at
most "4 bit sets and dlist operations" (i.e. a few dozen
instructions), reducing latency significantly and allowing us to lock
against interrupts cleanly from all APIs. Allocations and frees can
be done from ISRs now without limitation (well, obviously you can't
sleep, so "timeout" must be K_NO_WAIT).
Deterministic performance: there is no more "defragmentation" step
that must be manually managed. Block coalescing is done synchronously
at free time and takes constant time (strictly log4(num_levels)), as
the detection of four free "partner bits" is just a simple shift and
mask operation.
Cleaner behavior with odd sizes. The old code assumed that the
specified maximum size would be a power of four multiple of the
minimum size, making use of non-standard buffer sizes problematic.
This implementation re-aligns the sub-blocks at each level and can
handle situations wehre alignment restrictions mean fewer than 4x will
be available. If you want precise layout control, you can still
specify the sizes rigorously. It just doesn't break if you don't.
More portable: the original implementation made use of GNU assembler
macros embedded inline within C __asm__ statements. Not all
toolchains are actually backed by a GNU assembler even when the
support the GNU assembly syntax. This is pure C, albeit with some
hairy macros to expand the compile-time-computed values.
Related changes that had to be rolled into this patch for bisectability:
* The new allocator has a firm minimum block size of 8 bytes (to store
the dlist_node_t). It will "work" with smaller requested min_size
values, but obviously makes no firm promises about layout or how
many will be available. Unfortunately many of the tests were
written with very small 4-byte minimum sizes and to assume exactly
how many they could allocate. Bump the sizes to match the allocator
minimum.
* The mbox and pipes API made use of the internals of k_mem_block and
had to be ported to the new scheme. Blocks no longer store a
backpointer to the pool that allocated them (it's an integer ID in a
bitfield) , so if you want to "nullify" them you have to use the
data pointer.
* test_mbox_api had a bug were it was prematurely freeing k_mem_blocks
that it sent through the mailbox. This worked in the old allocator
because the memory wouldn't be touched when freed, but now we stuff
list pointers in there and the bug was exposed.
* Remove test_mpool_options: the options (related to defragmentation
behavior) tested no longer exist.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
Once all users of k_lifo migrate to k_queue this should no longer be
needed.
Change-Id: Ib8af40c57bf8feba7b06d6d891cfa57b44faad42
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
This makes k_fifo functions rely on k_queue and port k_poll to use
k_queue directly.
Once all users of k_fifo migrate to k_queue this should no longer be
needed.
Change-Id: Icf16d580f88d11b2cb89e1abd23ae314f43dbd20
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
This unifies k_fifo and k_lifo APIs thus making it more flexible regarding
where the data elements are inserted.
Change-Id: Icd6e2f62fc8b374c8273bb763409e9e22c40f9f8
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
k_poll() is similar to the POSIX poll() API in spirit in that it allows
a single thread to monitor multiple events without actively polling
them, but rather pending for one or more to become ready. Such events
can be a direct event, or kernel objects (currently only semaphores and
fifos).
When a kernel object being polled on is ready, it is not "given" to the
poller: the poller must then acquire it via the regular API for the
object (e.g. k_sem_take()). Only one thread can poll on a particular
object at one time. These restrictions mean that k_poll() is most
effective when a single thread monitors multiple events that are not
subject for contention. For example, being the sole reader on multiple
fifos, or the only thread being signalled by multiple semaphores, or a
combination of both.
Change-Id: I7035a9baf4aa016fb87afc5f5c0f5f8cb216480f
Signed-off-by: Benjamin Walsh <walsh.benj@gmail.com>
Make it depend on CONFIG_LEGACY_KERNEL being enabled.
Change-Id: Id5d3cd35a52d38bf7476ea8e51b71e2c687f0923
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
Also remove mentions of unified kernel in various places in the kernel,
samples and documentation.
Change-Id: Ice43bc73badbe7e14bae40fd6f2a302f6528a77d
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
include/ will be cleaned up in a subsequent patch.
Change-Id: If3609f5fc8562ec4a6fec4592aefeec155599cfb
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Make sure that kernel/unified, that is included in libs-y does not
built recursively through building kernel/ directory.
Make sure that any lib.a library is not included into libzephyr.a
and thus object modules from those lib.a files are linked only if a
function from that object module is referenced from the application.
Jira: ZEP-1025
Change-Id: Id3a3e96ca0b8abc9aedde0ffb9baa0164e380464
Signed-off-by: Dmitriy Korovkin <dmitriy.korovkin@windriver.com>
Added needed kconfig options. KERNEL_V2 selects MICROKERNEL to allow
middleware and application that differentiate between NANOKERNEL and
MICROKERNEL to run unmodified.
Build the unified/ kernel directory: do not touch the
nanokernel/microkernel directories.
Invoke sysgen for both microkernel and unified kernel. Only have sysgen
reference include/microkernel if building an original microkernel.
Change-Id: If74779146143434f7ee274bbef32d6c894b9f1a1
Signed-off-by: Benjamin Walsh <benjamin.walsh@windriver.com>
This commit creates the Makefiles that describe the object-bundles for
the kernel directory and every sub-directory below.
It also includes the misc Makefile.
Signed-off-by: Juan Manuel Cruz <juan.m.cruz.alcaraz@linux.intel.com>
Change-Id: I847e79a40ced0b1d8370b893cd95c15efc7e5147
Andy Ross