use C linkage where appropriate in headers

Assure that 'extern "C" { /../ }' do not cover files included from a
particular header file, and address minor issues resulting from this
change of order.

use C linkage where appropriate in headers

Assure that 'extern "C" { /../ }' do not cover files included from a
particular header file, and address minor issues resulting from this
change of order.

Dealing with C++ should delegate to the individual include file level,
rather than being imposed by the user of that file. For example,
forcing C linkage prevents __Generic macros being replaced with
overloaded static inline functions in C++ translation units.

Eliminate 'extern "C"' from files which do not declare any symbols
(e.g., only macros or struct types).

On the other hand, the headers check is too naive in assuming that all
headers must contain a 'extern "C"'. Such a check was added in commit
1ee492bdc4ff ("buildtools/chkincs: check missing C++ guards").
Since this current change results in many headers not containing such
a token, remove the check for 'extern "C"' until we have a better
implementation.

Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
Signed-off-by: David Marchand <david.marchand@redhat.com>

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cleanup compat header inclusions

With symbols going though experimental/stable stages, we accumulated
a lot of discrepancies about inclusion of the rte_compat.h header.

Some headers are including i

cleanup compat header inclusions

With symbols going though experimental/stable stages, we accumulated
a lot of discrepancies about inclusion of the rte_compat.h header.

Some headers are including it where unneeded, while others rely on
implicit inclusion.

Fix unneeded inclusions:
$ git grep -l include..rte_compat.h |
xargs grep -LE '__rte_(internal|experimental)' |
xargs sed -i -e '/#include..rte_compat.h/d'

Fix missing inclusion, by inserting rte_compat.h before the first
inclusion of a DPDK header:
$ git grep -lE '__rte_(internal|experimental)' |
xargs grep -L include..rte_compat.h |
xargs sed -i -e \
'0,/#include..\(rte_\|.*pmd.h.$\)/{
s/\(#include..\(rte_\|.*pmd.h.$\)\)/#include <rte_compat.h>\n\1/
}'

Fix missing inclusion, by inserting rte_compat.h after the last
inclusion of a non DPDK header:
$ for file in $(git grep -lE '__rte_(internal|experimental)' |
xargs grep -L include..rte_compat.h); do
tac $file > $file.$$
sed -i -e \
'0,/#include../{
s/\(#include..*$\)/#include <rte_compat.h>\n\n\1/
}' $file.$$
tac $file.$$ > $file
rm $file.$$
done

Fix missing inclusion, by inserting rte_compat.h after the header guard:
$ git grep -lE '__rte_(internal|experimental)' |
xargs grep -L include..rte_compat.h |
xargs sed -i -e \
'0,/#define/{
s/\(#define .*$\)/\1\n\n#include <rte_compat.h>/
}'

And finally, exclude rte_compat.h itself.
$ git checkout lib/eal/include/rte_compat.h

At the end of all this, we have a clean tree:
$ git grep -lE '__rte_(internal|experimental)' |
xargs grep -L include..rte_compat.h
buildtools/check-symbols.sh
devtools/checkpatches.sh
doc/guides/contributing/abi_policy.rst
doc/guides/rel_notes/release_20_11.rst
lib/eal/include/rte_compat.h

Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>

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service: tweak cycle statistics semantics

As a part of its service function, a service usually polls some kind
of source (e.g., an RX queue, a ring, an eventdev port, or a timer
wheel) to retrieve o

service: tweak cycle statistics semantics

As a part of its service function, a service usually polls some kind
of source (e.g., an RX queue, a ring, an eventdev port, or a timer
wheel) to retrieve one or more items of work.

In low-load situations, the service framework reports a significant
amount of cycles spent for all running services, despite the fact they
have performed little or no actual work.

The per-call cycle expenditure for an idle service (i.e., a service
currently without pending jobs) is typically very low. Polling an
empty ring or RX queue is inexpensive. However, since the service
function call frequency on an idle or lightly loaded lcore is going to
be very high indeed, the service function calls' cycles adds up to a
significant amount. The only thing preventing the idle services'
cycles counters to make up 100% of the available CPU cycles is the
overhead of the service framework itself.

If the RTE_SERVICE_ATTR_CYCLES or RTE_SERVICE_LCORE_ATTR_CYCLES are
used to estimate service core load, the cores may look very busy when
the system is mostly doing nothing useful at all.

This patch allows for an idle service to indicate that no actual work
was performed during a particular service function call (by returning
-EAGAIN). In such cases the RTE_SERVICE_ATTR_CYCLES and
RTE_SERVICE_LCORE_ATTR_CYCLES values are not incremented.

The convention of returning -EAGAIN for idle services may in the
future also be used to have the lcore enter a short sleep, or reduce
its operating frequency, in case all services are currently idle.

This change is backward-compatible.

Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Harry van Haaren <harry.van.haaren@intel.com>

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lib: remove librte_ prefix from directory names

There is no reason for the DPDK libraries to all have 'librte_' prefix on
the directory names. This prefix makes the directory names longer and also
m

lib: remove librte_ prefix from directory names

There is no reason for the DPDK libraries to all have 'librte_' prefix on
the directory names. This prefix makes the directory names longer and also
makes it awkward to add features referring to individual libraries in the
build - should the lib names be specified with or without the prefix.
Therefore, we can just remove the library prefix and use the library's
unique name as the directory name, i.e. 'eal' rather than 'librte_eal'

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>

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