eal: introduce integer divide through reciprocal

In some use cases of integer division, denominator remains constant and
numerator varies. It is possible to optimize division for such specific
scenarios.

The librte_sched uses rte_reciprocal to optimize division so, moving it to
eal/common would allow other libraries and applications to use it.

Signed-off-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>

lib/librte_eal/bsdapp/eal/Makefile

@@ -57,6 +57,7 @@ SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += malloc_elem.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += malloc_heap.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += rte_keepalive.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += rte_service.c
+SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += rte_reciprocal.c
 
 # from arch dir
 SRCS-$(CONFIG_RTE_EXEC_ENV_BSDAPP) += rte_cpuflags.c

lib/librte_eal/common/Makefile

@@ -16,6 +16,7 @@ INC += rte_pci_dev_feature_defs.h rte_pci_dev_features.h
 INC += rte_malloc.h rte_keepalive.h rte_time.h
 INC += rte_service.h rte_service_component.h
 INC += rte_bitmap.h rte_vfio.h rte_hypervisor.h rte_test.h
+INC += rte_reciprocal.h
 
 GENERIC_INC := rte_atomic.h rte_byteorder.h rte_cycles.h rte_prefetch.h
 GENERIC_INC += rte_spinlock.h rte_memcpy.h rte_cpuflags.h rte_rwlock.h

lib/librte_eal/linuxapp/eal/Makefile

@@ -64,6 +64,7 @@ SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += malloc_elem.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += malloc_heap.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += rte_keepalive.c
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += rte_service.c
+SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += rte_reciprocal.c
 
 # from arch dir
 SRCS-$(CONFIG_RTE_EXEC_ENV_LINUXAPP) += rte_cpuflags.c

lib/librte_eal/rte_eal_version.map

@@ -206,7 +206,7 @@ DPDK_18.02 {
 	rte_hypervisor_get;
 	rte_hypervisor_get_name;
 	rte_vfio_clear_group;
-
+	rte_reciprocal_value;
 } DPDK_17.11;
 
 EXPERIMENTAL {

lib/librte_sched/Makefile

@@ -26,10 +26,8 @@ LIBABIVER := 1
 # all source are stored in SRCS-y
 #
 SRCS-$(CONFIG_RTE_LIBRTE_SCHED) += rte_sched.c rte_red.c rte_approx.c
-SRCS-$(CONFIG_RTE_LIBRTE_SCHED) += rte_reciprocal.c
 
 # install includes
 SYMLINK-$(CONFIG_RTE_LIBRTE_SCHED)-include := rte_sched.h rte_sched_common.h rte_red.h rte_approx.h
-SYMLINK-$(CONFIG_RTE_LIBRTE_SCHED)-include += rte_reciprocal.h
 
 include $(RTE_SDK)/mk/rte.lib.mk

lib/librte_sched/rte_sched.c

@@ -14,11 +14,11 @@
 #include <rte_branch_prediction.h>
 #include <rte_mbuf.h>
 #include <rte_bitmap.h>
+#include <rte_reciprocal.h>
 
 #include "rte_sched.h"
 #include "rte_sched_common.h"
 #include "rte_approx.h"
-#include "rte_reciprocal.h"
 
 #ifdef __INTEL_COMPILER
 #pragma warning(disable:2259) /* conversion may lose significant bits */