Commit Graph

120 Commits

Author SHA1 Message Date
Honnappa Nagarahalli
47bec9a5ca ring: add zero copy API
Add zero-copy APIs. These APIs provide the capability to
copy the data to/from the ring memory directly, without
having a temporary copy (for ex: an array of mbufs on
the stack). Use cases that involve copying large amount
of data to/from the ring can benefit from these APIs.

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Dharmik Thakkar <dharmik.thakkar@arm.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
2020-10-29 14:13:31 +01:00
Bruce Richardson
63b3907833 build: remove library name from version map file name
Since each version map file is contained in the subdirectory of the library
it refers to, there is no need to include the library name in the filename.
This makes things simpler in case of library renaming.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Luca Boccassi <bluca@debian.org>
Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Acked-by: Rosen Xu <rosen.xu@intel.com>
2020-10-19 22:13:59 +02:00
Ciara Power
ec260aa3ad config: remove default configs used with make
Make is not supported for compiling DPDK, the config files are no
longer needed.

Signed-off-by: Ciara Power <ciara.power@intel.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
2020-09-08 00:11:30 +02:00
Ciara Power
3cc6ecfdfe build: remove makefiles
A decision was made [1] to no longer support Make in DPDK, this patch
removes all Makefiles that do not make use of pkg-config, along with
the mk directory previously used by make.

[1] https://mails.dpdk.org/archives/dev/2020-April/162839.html

Signed-off-by: Ciara Power <ciara.power@intel.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
2020-09-08 00:09:50 +02:00
Thomas Monjalon
4f86c0ba19 version: 20.11-rc0
Start a new release cycle with empty release notes.

The ABI version becomes 21.0.
The ABI major is back to normal, having only one number (21 vs 20.0).
The map files are updated to the new ABI major number (21).
The ABI exceptions are dropped.
Travis ABI check is disabled because compatibility is not preserved.

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Ray Kinsella <mdr@ashroe.eu>
2020-08-12 11:32:16 +02:00
Feifei Wang
2d6ed071a8 ring: use custom element for fixed size API
Use rte_ring_xxx_elem_xxx APIs to replace legacy API implementation.
This reduces code duplication and improves code maintenance.

Tests done on Arm, x86 [1] and PPC [2] do not indicate performance
degradation.
[1] https://mails.dpdk.org/archives/dev/2020-July/173780.html
[2] https://mails.dpdk.org/archives/dev/2020-July/173863.html

Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Tested-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Tested-by: David Christensen <drc@linux.vnet.ibm.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
2020-07-09 17:22:36 +02:00
Feifei Wang
019bffab51 ring: remove experimental flag from custom element API
Remove the experimental tag for rte_ring_xxx_elem APIs that have been
around for 2 releases.

Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
2020-07-09 17:22:29 +02:00
Feifei Wang
2f86fb666e ring: remove experimental flag from reset API
Remove the experimental tag for rte_ring_reset API that have been around
for 4 releases.

Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
2020-07-09 17:21:54 +02:00
Morten Brørup
4b7284a71f ring: optimize empty test
Testing if the ring is empty is as simple as comparing the producer and
consumer pointers.

In theory, this optimization reduces the number of potential cache misses
from 3 to 2 by not having to read r->mask in rte_ring_count().

The modification of this function were also discussed in the RFC here:
https://mails.dpdk.org/archives/dev/2020-April/165752.html

Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
2020-07-01 11:46:09 +02:00
Morten Brørup
36e3cfbbef ring: cleanup coding style
Fix coding style violations that checkpatch will complain about.

Add missing "int" after "unsigned".
Add missing spaces around "+=" and "+".
Remove superfluous type cast of numerical constant.

Suggested-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
2020-07-01 11:46:09 +02:00
Feifei Wang
708d904451 ring: fix tail in peek API for ST mode
The value of *tail should be the prod->tail not prod->head. After
modification, it can record 'tail' so head/tail can be updated
accordingly.

Fixes: 664ff4b172 ("ring: introduce peek style API")

Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
2020-07-01 10:41:19 +02:00
Feifei Wang
c8d909aeb7 ring: fix bulk enqueue for HTS/RTS ring modes
Remove the unwanted call to "_rte_ring_do_enqueue_elem" to allow for
correct handling of RTS/HTS modes.

Fixes: e6ba4731c0 ("ring: introduce RTS ring mode")

Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
2020-07-01 10:41:19 +02:00
Stephen Hemminger
3e71b3d456 ring: check flag settings for future proofing
All API's should check that they support the flag values passed.
These checks ensure that the extra bits can safely be used
without risk of ABI breakage.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
2020-06-16 17:46:39 +02:00
Ferruh Yigit
867b49d17a ring: fix build for gcc O1 optimization
Can be reproduced with "make EXTRA_CFLAGS='-O1'" command using
gcc (GCC) 9.3.1 20200408 (Red Hat 9.3.1-2)

Two build errors:
1)
In file included from .../build/include/rte_ring_elem.h:1093,
                 from .../lib/librte_rcu/rte_rcu_qsbr.c:21:
../lib/librte_rcu/rte_rcu_qsbr.c: In function ‘rte_rcu_qsbr_dq_reclaim’:
.../build/include/rte_ring_peek.h:282:22:
    error: ‘avail’ may be used uninitialized in this function
           [-Werror=maybe-uninitialized]
  282 |   *available = avail - n;
      |                ~~~~~~^~~
./build/include/rte_ring_peek.h:259:11: note: ‘avail’ was declared here
  259 |  uint32_t avail, head, next;
      |           ^~~~~

2)
In file included from .../build/include/rte_ring_elem.h:1093,
                 from .../build/include/rte_ring.h:405,
                 from .../app/test/test_ring_stress.h:13,
                 from .../app/test/test_ring_stress_impl.h:5,
                 from .../app/test/test_ring_peek_stress.c:5:
.../app/test/test_ring_peek_stress.c: In function ‘_st_ring_enqueue_bulk’:
.../build/include/rte_ring_peek.h:80:22:
    error: ‘free’ may be used uninitialized in this function
           [-Werror=maybe-uninitialized]
   80 |   *free_space = free - n;
      |                 ~~~~~^~~
.../build/include/rte_ring_peek.h:60:11: note: ‘free’ was declared here
   60 |  uint32_t free, head, next;
      |           ^~~~

The cases shouldn't be hit, and it looks like there is already logic
error if it has been hit, but assigning 'avail' & 'free' to '0' to fix
the build error.

Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
2020-05-11 19:20:54 +02:00
David Marchand
2ead29e1d6 ring: fix build with -Wswitch-enum
Some popular vswitch implementation might use a gcc option that
complains about missing enums in switch statements.
Fix this by listing all possible values.

Fixes: 664ff4b172 ("ring: introduce peek style API")

Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
2020-04-28 11:34:40 +02:00
Konstantin Ananyev
664ff4b172 ring: introduce peek style API
For rings with producer/consumer in RTE_RING_SYNC_ST, RTE_RING_SYNC_MT_HTS
mode, provide an ability to split enqueue/dequeue operation
into two phases:
      - enqueue/dequeue start
      - enqueue/dequeue finish
That allows user to inspect objects in the ring without removing
them from it (aka MT safe peek).

Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Acked-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
2020-04-21 12:52:55 +02:00
Konstantin Ananyev
1cc363b8ce ring: introduce HTS ring mode
Introduce head/tail sync mode for MT ring synchronization.
In that mode enqueue/dequeue operation is fully serialized:
only one thread at a time is allowed to perform given op.
Suppose to reduce stall times in case when ring is used on
overcommitted cpus (multiple active threads on the same cpu).

Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Acked-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
2020-04-21 12:52:55 +02:00
Konstantin Ananyev
e6ba4731c0 ring: introduce RTS ring mode
Introduce relaxed tail sync (RTS) mode for MT ring synchronization.
Aim to reduce stall times in case when ring is used on
overcommited cpus (multiple active threads on the same cpu).
The main difference from original MP/MC algorithm is that
tail value is increased not by every thread that finished enqueue/dequeue,
but only by the last one.
That allows threads to avoid spinning on ring tail value,
leaving actual tail value change to the last thread in the update queue.

Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Acked-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
2020-04-21 12:52:55 +02:00
Konstantin Ananyev
ebff988d0c ring: prepare ring to allow new sync schemes
To make these preparations two main things are done:
- Change from *single* to *sync_type* to allow different
  synchronisation schemes to be applied.
  Mark *single* as deprecated in comments.
  Add new functions to allow user to query ring sync types.
  Replace direct access to *single* with appropriate function call.
- Move actual rte_ring and related structures definitions into a
  separate file: <rte_ring_core.h>. It allows to refer contents
  of <rte_ring_elem.h> from <rte_ring.h> without introducing a
  circular dependency.

Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Acked-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
2020-04-21 11:34:09 +02:00
Pavan Nikhilesh
acec04c4b2 build: disable experimental API check internally
Remove setting ALLOW_EXPERIMENTAL_API individually for each Makefile and
meson.build. Instead, enable ALLOW_EXPERIMENTAL_API flag across app, lib
and drivers.
This changes reduces the clutter across the project while still
maintaining the functionality of ALLOW_EXPERIMENTAL_API i.e. warning
external applications about experimental API usage.

Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
Acked-by: Hemant Agrawal <hemant.agrawal@nxp.com>
Signed-off-by: David Marchand <david.marchand@redhat.com>
2020-04-14 16:22:34 +02:00
Phil Yang
3ba51478a3 ring: fix unaligned memory access on aarch32
The 32-bit arm machine doesn't support unaligned memory access. It
will cause a bus error on aarch32 with the custom element size ring.

Thread 1 "test" received signal SIGBUS, Bus error.
__rte_ring_enqueue_elems_64 (n=1, obj_table=0xf5edfe41, prod_head=0, \
r=0xf5edfb80) at /build/dpdk/build/include/rte_ring_elem.h:177
177                             ring[idx++] = obj[i++];

Fixes: cc4b218790 ("ring: support configurable element size")

Signed-off-by: Phil Yang <phil.yang@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
2020-03-19 16:18:09 +01:00
Honnappa Nagarahalli
ae122e5079 ring: fix API documentation
Correct the documentation for obj_table in rte_ring_xxx_elem APIs.

Fixes: cc4b218790 ("ring: support configurable element size")

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
2020-02-15 16:41:33 +01:00
Thomas Monjalon
03d24a16f7 ring: fix namespace prefix of inline functions
When adding custom element size feature, some internal inline functions
were added in a public header without rte_ prefix.
It is fixed by adding __rte_ring_.

Fixes: cc4b218790 ("ring: support configurable element size")

Reported-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
2020-02-06 11:48:32 +01:00
Honnappa Nagarahalli
cc4b218790 ring: support configurable element size
Current APIs assume ring elements to be pointers. However, in many
use cases, the size can be different. Add new APIs to support
configurable ring element sizes.

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Dharmik Thakkar <dharmik.thakkar@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
2020-01-19 19:32:48 +01:00
Pawel Modrak
85ff364f3b build: align symbols with global ABI version
Merge all versions in linker version script files to DPDK_20.0.

This commit was generated by running the following command:

:~/DPDK$ buildtools/update-abi.sh 20.0

Signed-off-by: Pawel Modrak <pawelx.modrak@intel.com>
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>
2019-11-20 23:05:39 +01:00
Anatoly Burakov
fbaf943887 build: remove individual library versions
Since the library versioning for both stable and experimental ABI's is
now managed globally, the LIBABIVER and version variables no longer
serve any useful purpose, and can be removed.

The replacement in Makefiles was done using the following regex:

	^(#.*\n)?LIBABIVER\s*:=\s*\d+\n(\s*\n)?

(LIBABIVER := numbers, optionally preceded by a comment and optionally
succeeded by an empty line)

The replacement for meson files was done using the following regex:

	^(#.*\n)?version\s*=\s*\d+\n(\s*\n)?

(version = numbers, optionally preceded by a comment and optionally
succeeded by an empty line)

[David]: those variables are manually removed for the files:
- drivers/common/qat/Makefile
- lib/librte_eal/meson.build
[David]: the LIBABIVER is restored for the external ethtool example
library.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>
2019-11-20 23:05:39 +01:00
Gavin Hu
272d87b01b ring: add reset function for flushing
Currently, the flush is done by dequeuing the ring in a while loop. It is
much simpler to flush the queue by resetting the head and tail indices.

Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
2019-07-17 19:51:56 +02:00
Anatoly Burakov
028669bc9f eal: hide shared memory config
Now that everything that has ever accessed the shared memory
config is doing so through the public API's, we can make it
internal. Since we're removing quite a few headers from
rte_eal_memconfig.h, we need to add them back in places
where this header is used.

This bumps the ABI, so also change all build files and make
update documentation.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: David Marchand <david.marchand@redhat.com>
2019-07-06 10:32:34 +02:00
Anatoly Burakov
a36f5ce06e eal: add API to lock/unlock tailq list
Currently, locking/unlocking the TAILQ list requires direct
access to the shared memory config. Add an API to do the same,
and search-and-replace all usages.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: David Marchand <david.marchand@redhat.com>
2019-07-05 22:13:23 +02:00
Xiaolong Ye
7f9f46d6ce ring: remove unnecessary forward declaration
As memzone.h is introduced by
commit 38c9817ee1 ("mempool: adjust name size in related data types"),
forward declaration for rte_memzone is no longer needed.

Signed-off-by: Xiaolong Ye <xiaolong.ye@intel.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
2019-06-04 13:09:51 +02:00
John McNamara
8bd5f07c7a doc: fix spelling reported by aspell in comments
Fix spelling errors in the doxygen docs.

Signed-off-by: John McNamara <john.mcnamara@intel.com>
2019-05-03 00:38:14 +02:00
Bruce Richardson
f9acaf84e9 replace snprintf with strlcpy without adding extra include
For files that already have rte_string_fns.h included in them, we can
do a straight replacement of snprintf(..."%s",...) with strlcpy. The
changes in this patch were auto-generated via command:

spatch --sp-file devtools/cocci/strlcpy-with-header.cocci --dir . --in-place

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
2019-04-04 22:45:54 +02:00
Gage Eads
97c48e71fc ring: fix namesize macro documentation block
'/**<' style comments apply to the previous member, which caused doxygen to
emit the RTE_RING_NAMESIZE documentation for RTE_RING_MZ_PREFIX.

Fixes: 38c9817ee1 ("mempool: adjust name size in related data types")
Cc: stable@dpdk.org

Signed-off-by: Gage Eads <gage.eads@intel.com>
2019-04-04 22:06:16 +02:00
Stephen Hemminger
c0c055f5f7 ring: fix an error message
Log message should end with newline.

Fixes: 4e32101f9b ("ring: support freeing")

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Reviewed-by: Rami Rosen <ramirose@gmail.com>
2019-04-03 18:39:16 +02:00
Gavin Hu
85cffb2ecc ring: enforce reading tail before slots
In weak memory models, like arm64, reading the prod.tail may get
reordered after reading the ring slots, which corrupts the ring and
stale data is observed.

This issue was reported by NXP on 8-A72 DPAA2 board. The problem is most
likely caused by missing the acquire semantics when reading
prod.tail (in SC dequeue) which makes it possible to read a
stale value from the ring slots.

For MP (and MC) case, rte_atomic32_cmpset() already provides the required
ordering. For SP case, the control depependency between if-statement (which
depends on the read of r->cons.tail) and the later stores to the ring slots
make RMB unnecessary. About the control dependency, read more at:
https://www.cl.cam.ac.uk/~pes20/ppc-supplemental/test7.pdf

This patch is adding the required read barrier to prevent reading the ring
slots get reordered before reading prod.tail for SC case.

Fixes: c9fb3c6289 ("ring: move code in a new header file")
Cc: stable@dpdk.org

Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Tested-by: Nipun Gupta <nipun.gupta@nxp.com>
Acked-by: Nipun Gupta <nipun.gupta@nxp.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
2019-03-28 01:22:04 +01:00
Gavin Hu
49594a6314 ring/c11: relax ordering for load and store of the head
When calling __atomic_compare_exchange_n, use relaxed ordering for the
success case, as multiple producers/consumers do not release updates to
each other so no need for acquire or release ordering.

Because the thread fence in place, ordering for the first iteration can
be relaxed.

Run the ring perf test on the following testbed:
HW: ThunderX2 B0 CPU CN9975 v2.0, 2 sockets, 28core,4 threads/core,2.5GHz
OS: Ubuntu 16.04.5 LTS, Kernel: 4.15.0-36-generic
DPDK: 18.08, Configuration: arm64-armv8a-linuxapp-gcc
gcc: 8.1.0
$sudo ./test/test/test -l 16-19,44-47,72-75,100-103 -n 4 \
--socket-mem=1024 -- -i

Without the patch:
*** Testing using two physical cores ***
SP/SC bulk enq/dequeue (size: 8): 5.75
MP/MC bulk enq/dequeue (size: 8): 10.18
SP/SC bulk enq/dequeue (size: 32): 1.80
MP/MC bulk enq/dequeue (size: 32): 2.34

With the patch:
*** Testing using two physical cores ***
SP/SC bulk enq/dequeue (size: 8): 5.59
MP/MC bulk enq/dequeue (size: 8): 10.54
SP/SC bulk enq/dequeue (size: 32): 1.73
MP/MC bulk enq/dequeue (size: 32): 2.38

No significant improvement, nor regression was seen, as the optimisation
is not at the critical path.

Fixes: 39368ebfc6 ("ring: introduce C11 memory model barrier option")
Cc: stable@dpdk.org

Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
2018-11-13 17:00:58 +01:00
Gavin Hu
86757c2c3e ring/c11: keep deterministic order allowing retry to work
Use case scenario:
1) Thread 1 is enqueuing. It reads prod.head and gets stalled for some
   reasons (running out of cpu time, preempted,...)
2) Thread 2 is enqueuing. It succeeds in enqueuing and moves prod.head
   forward.
3) Thread 3 is dequeuing. It succeeds in dequeuing and moves the cons.tail
   beyond the prod.head read by thread 1.
4) Thread 1 is re-scheduled. It reads cons.tail.

cpu1(producer)      cpu2(producer)          cpu3(consumer)
load r->prod.head
    ^               load r->prod.head
    |               load r->cons.tail
    |               store r->prod.head(+n)
  stalled           <-- enqueue ----->
    |               store r->prod.tail(+n)
    |                                        load r->cons.head
    |                                        load r->prod.tail
    |                                        store r->cons.head(+n)
    |                                        <...dequeue.....>
    v                                        store r->cons.tail(+n)
load r->cons.tail

For thread 1, the __atomic_compare_exchange_n detects the outdated
prod.head and retry the flow with the new one. This retry flow works ok on
strong ordering platform(eg:x86). But for weak ordering platforms(arm,
ppc), loading cons.tail and prod.head might be re-ordered, prod.head is new
but cons.tail becomes too old, the retry flow, based on the detection of
outdated head, does not trigger as expected, thus the outdate cons.tail
causes wrong free_entries.

Similarly, for dequeuing, outdated prod.tail leads to wrong avail_entries.

The fix is to keep the deterministic order of two loads allowing the retry
to work.

Run the ring perf test on the following testbed:
HW: ThunderX2 B0 CPU CN9975 v2.0, 2 sockets, 28core, 4 threads/core, 2.5GHz
OS: Ubuntu 16.04.5 LTS, Kernel: 4.15.0-36-generic
DPDK: 18.08, Configuration: arm64-armv8a-linuxapp-gcc
gcc: 8.1.0
$sudo ./test/test/test -l 16-19,44-47,72-75,100-103 -n 4 \
--socket-mem=1024 -- -i

Without the patch:
*** Testing using two physical cores ***
SP/SC bulk enq/dequeue (size: 8): 5.64
MP/MC bulk enq/dequeue (size: 8): 9.58
SP/SC bulk enq/dequeue (size: 32): 1.98
MP/MC bulk enq/dequeue (size: 32): 2.30

With the patch:
*** Testing using two physical cores ***
SP/SC bulk enq/dequeue (size: 8): 5.75
MP/MC bulk enq/dequeue (size: 8): 10.18
SP/SC bulk enq/dequeue (size: 32): 1.80
MP/MC bulk enq/dequeue (size: 32): 2.34

The results showed the thread fence degrade the performance slightly, but
it is required for correctness.

Fixes: 39368ebfc6 ("ring: introduce C11 memory model barrier option")
Cc: stable@dpdk.org

Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
2018-11-13 16:57:58 +01:00
Gavin Hu
047adc1724 ring/c11: move atomic load of head above the loop
In __rte_ring_move_prod_head, move the __atomic_load_n up and out of
the do {} while loop as upon failure the old_head will be updated,
another load is costly and not necessary.

This helps a little on the latency,about 1~5%.

 Test result with the patch(two cores):
 SP/SC bulk enq/dequeue (size: 8): 5.64
 MP/MC bulk enq/dequeue (size: 8): 9.58
 SP/SC bulk enq/dequeue (size: 32): 1.98
 MP/MC bulk enq/dequeue (size: 32): 2.30

Fixes: 39368ebfc6 ("ring: introduce C11 memory model barrier option")
Cc: stable@dpdk.org

Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Reviewed-by: Jia He <justin.he@arm.com>
Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Tested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
2018-11-05 14:34:27 +01:00
Gavin Hu
9ed8770628 ring/c11: synchronize load and store of the tail
Synchronize the load-acquire of the tail and the store-release
within update_tail, the store release ensures all the ring operations,
enqueue or dequeue, are seen by the observers on the other side as soon
as they see the updated tail. The load-acquire is needed here as the
data dependency is not a reliable way for ordering as the compiler might
break it by saving to temporary values to boost performance.
When computing the free_entries and avail_entries, use atomic semantics
to load the heads and tails instead.

The patch was benchmarked with test/ring_perf_autotest and it decreases
the enqueue/dequeue latency by 5% ~ 27.6% with two lcores, the real gains
are dependent on the number of lcores, depth of the ring, SPSC or MPMC.
For 1 lcore, it also improves a little, about 3 ~ 4%.
It is a big improvement, in case of MPMC, with two lcores and ring size
of 32, it saves latency up to (3.26-2.36)/3.26 = 27.6%.

This patch is a bug fix, while the improvement is a bonus. In our analysis
the improvement comes from the cacheline pre-filling after hoisting load-
acquire from _atomic_compare_exchange_n up above.

The test command:
$sudo ./test/test/test -l 16-19,44-47,72-75,100-103 -n 4 --socket-mem=\
1024 -- -i

Test result with this patch(two cores):
 SP/SC bulk enq/dequeue (size: 8): 5.86
 MP/MC bulk enq/dequeue (size: 8): 10.15
 SP/SC bulk enq/dequeue (size: 32): 1.94
 MP/MC bulk enq/dequeue (size: 32): 2.36

In comparison of the test result without this patch:
 SP/SC bulk enq/dequeue (size: 8): 6.67
 MP/MC bulk enq/dequeue (size: 8): 13.12
 SP/SC bulk enq/dequeue (size: 32): 2.04
 MP/MC bulk enq/dequeue (size: 32): 3.26

Fixes: 39368ebfc6 ("ring: introduce C11 memory model barrier option")
Cc: stable@dpdk.org

Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Reviewed-by: Jia He <justin.he@arm.com>
Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Tested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
2018-11-05 14:34:19 +01:00
Phil Yang
ede56cc18d config: rename option for C11 memory model
Keep only single config option RTE_USE_C11_MEM_MODEL for C11 memory
model, so all modules can leverage C11 atomic extension by enable this
option.

Signed-off-by: Phil Yang <phil.yang@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
2018-10-26 18:09:22 +02:00
Ferruh Yigit
73aa5c1332 ring: add library version to meson build
Fixes: a3d6026711 ("ring: relax alignment constraint on ring structure")
Cc: stable@dpdk.org

Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Luca Boccassi <bluca@debian.org>
2018-10-25 14:30:05 +02:00
Honnappa Nagarahalli
4a6e683c4c ring: clarify preemptible nature of algorithm
rte_ring implementation is not preemptible only under certain
circumstances. This clarification is helpful for data plane and
control plane communication using rte_ring.

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
2018-08-05 20:06:10 +02:00
Andy Green
ea771bc2a9 ring: fix sign conversion warning
On gcc 5.4.0 / native aarch64 from Ubuntu 16.04:

In function '__rte_ring_do_dequeue':
rte_ring.h: 385:35: warning:
conversion to 'int' from 'unsigned int' may change
the sign of the result [-Wsign-conversion]
  n = __rte_ring_move_cons_head(r, is_sc, n, behavior,
                                   ^

Fixes: e8ed5056c8 ("ring: remove signed type flip-flopping")
Cc: stable@dpdk.org

Signed-off-by: Andy Green <andy@warmcat.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
2018-07-26 16:11:51 +02:00
Andy Green
44c41b8577 ring: fix declaration after statement
On gcc 5.4.0 / native aarch64 from Ubuntu 16.04:

In function '__rte_ring_move_prod_head':
rte_ring_c11_mem.h:69:3: warning:
ISO C90 forbids mixed declarations and code
[-Wdeclaration-after-statement]
   const uint32_t cons_tail = r->cons.tail;
   ^

In function '__rte_ring_move_cons_head':
rte_ring_c11_mem.h:136:3: warning:
ISO C90 forbids mixed declarations and code
[-Wdeclaration-after-statement]
   const uint32_t prod_tail = r->prod.tail;
   ^

Fixes: 39368ebfc6 ("ring: introduce C11 memory model barrier option")
Cc: stable@dpdk.org

Signed-off-by: Andy Green <andy@warmcat.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
2018-07-26 16:11:51 +02:00
Andy Green
e8ed5056c8 ring: remove signed type flip-flopping
GCC 8.1 warns:

rte_ring.h:350:46:
warning: conversion to 'uint32_t' {aka 'unsigned int'}
from 'int' may change the sign of the result
[-Wsign-conversion]
  update_tail(&r->prod, prod_head, prod_next, is_sp, 1);

The visible apis take unsigned int, then call a private
api taking an int, which finally calls an api taking an
unsigned int.

Convert the private api to take unsigned int removing
5 x warning similar to that shown above.

Fixes: 0dfc98c507 ("ring: separate out head index manipulation")
Cc: stable@dpdk.org

Signed-off-by: Andy Green <andy@warmcat.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
2018-05-21 00:20:16 +02:00
Andy Green
712a3db0b5 ring: remove useless variables
There were warnings with GCC 8.1:

In function '__rte_ring_move_prod_head':
rte_ring_generic.h:76:3:
warning: ISO C90 forbids mixed declarations and code
[-Wdeclaration-after-statement]
   const uint32_t cons_tail = r->cons.tail;
   ^~~~~

In function '__rte_ring_move_cons_head':
rte_ring_generic.h:147:3:
warning: ISO C90 forbids mixed declarations and code
[-Wdeclaration-after-statement]
   const uint32_t prod_tail = r->prod.tail;

Fixes: 0dfc98c507 ("ring: separate out head index manipulation")
Cc: stable@dpdk.org

Signed-off-by: Andy Green <andy@warmcat.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
2018-05-21 00:20:12 +02:00
Olivier Matz
a3d6026711 ring: relax alignment constraint on ring structure
The initial objective of
commit d9f0d3a1ff ("ring: remove split cacheline build setting")
was to add an empty cache line between the producer and consumer
data (on platform with cache line size = 64B), preventing from
having them on adjacent cache lines.

Following discussion on the mailing list, it appears that this
also imposes an alignment constraint that is not required.

This patch removes the extra alignment constraint and adds the
empty cache lines using padding fields in the structure. The
size of rte_ring structure and the offset of the fields remain
the same on platforms with cache line size = 64B:

  rte_ring = 384
  rte_ring.name = 0
  rte_ring.flags = 32
  rte_ring.memzone = 40
  rte_ring.size = 48
  rte_ring.mask = 52
  rte_ring.prod = 128
  rte_ring.cons = 256

But it has an impact on platform where cache line size is 128B:

  rte_ring = 384        -> 768
  rte_ring.name = 0
  rte_ring.flags = 32
  rte_ring.memzone = 40
  rte_ring.size = 48
  rte_ring.mask = 52
  rte_ring.prod = 128   -> 256
  rte_ring.cons = 256   -> 512

Suggested-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
2018-04-18 00:24:22 +02:00
Pavan Nikhilesh
3e8ea3d3d4 lib: remove unused map symbols
Signed-off-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Hemant Agrawal <hemant.agrawal@nxp.com>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>
2018-02-13 14:55:01 +01:00
Jia He
9ffdaaa122 ring: convert license headers to SPDX tags
Signed-off-by: Jia He <jia.he@hxt-semitech.com>
Acked-by: Hemant Agrawal <hemant.agrawal@nxp.com>
2018-02-01 01:46:45 +01:00
Bruce Richardson
6c9457c279 build: replace license text with SPDX tag
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Luca Boccassi <bluca@debian.org>
2018-01-30 21:58:59 +01:00