diff --git a/lib/librte_sched/rte_sched.c b/lib/librte_sched/rte_sched.c index 89007ad117..1609ea878e 100644 --- a/lib/librte_sched/rte_sched.c +++ b/lib/librte_sched/rte_sched.c @@ -47,6 +47,7 @@ #include "rte_bitmap.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 */ @@ -67,6 +68,11 @@ #define RTE_SCHED_PIPE_INVALID UINT32_MAX #define RTE_SCHED_BMP_POS_INVALID UINT32_MAX +/* Scaling for cycles_per_byte calculation + * Chosen so that minimum rate is 480 bit/sec + */ +#define RTE_SCHED_TIME_SHIFT 8 + struct rte_sched_subport { /* Token bucket (TB) */ uint64_t tb_time; /* time of last update */ @@ -220,7 +226,7 @@ struct rte_sched_port { uint64_t time_cpu_cycles; /* Current CPU time measured in CPU cyles */ uint64_t time_cpu_bytes; /* Current CPU time measured in bytes */ uint64_t time; /* Current NIC TX time measured in bytes */ - double cycles_per_byte; /* CPU cycles per byte */ + struct rte_reciprocal inv_cycles_per_byte; /* CPU cycles per byte */ /* Scheduling loop detection */ uint32_t pipe_loop; @@ -615,7 +621,7 @@ struct rte_sched_port * rte_sched_port_config(struct rte_sched_port_params *params) { struct rte_sched_port *port = NULL; - uint32_t mem_size, bmp_mem_size, n_queues_per_port, i; + uint32_t mem_size, bmp_mem_size, n_queues_per_port, i, cycles_per_byte; /* Check user parameters. Determine the amount of memory to allocate */ mem_size = rte_sched_port_get_memory_footprint(params); @@ -666,7 +672,10 @@ rte_sched_port_config(struct rte_sched_port_params *params) port->time_cpu_cycles = rte_get_tsc_cycles(); port->time_cpu_bytes = 0; port->time = 0; - port->cycles_per_byte = ((double) rte_get_tsc_hz()) / ((double) params->rate); + + cycles_per_byte = (rte_get_tsc_hz() << RTE_SCHED_TIME_SHIFT) + / params->rate; + port->inv_cycles_per_byte = rte_reciprocal_value(cycles_per_byte); /* Scheduling loop detection */ port->pipe_loop = RTE_SCHED_PIPE_INVALID; @@ -2093,11 +2102,15 @@ rte_sched_port_time_resync(struct rte_sched_port *port) { uint64_t cycles = rte_get_tsc_cycles(); uint64_t cycles_diff = cycles - port->time_cpu_cycles; - double bytes_diff = ((double) cycles_diff) / port->cycles_per_byte; + uint64_t bytes_diff; + + /* Compute elapsed time in bytes */ + bytes_diff = rte_reciprocal_divide(cycles_diff << RTE_SCHED_TIME_SHIFT, + port->inv_cycles_per_byte); /* Advance port time */ port->time_cpu_cycles = cycles; - port->time_cpu_bytes += (uint64_t) bytes_diff; + port->time_cpu_bytes += bytes_diff; if (port->time < port->time_cpu_bytes) port->time = port->time_cpu_bytes;