diff options
Diffstat (limited to 'net/sched/sch_generic.c')
| -rw-r--r-- | net/sched/sch_generic.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index 5d81a4478514..ffad48109a22 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -25,6 +25,7 @@ #include <linux/rcupdate.h> #include <linux/list.h> #include <linux/slab.h> +#include <net/sch_generic.h> #include <net/pkt_sched.h> #include <net/dst.h> @@ -896,3 +897,39 @@ void dev_shutdown(struct net_device *dev) WARN_ON(timer_pending(&dev->watchdog_timer)); } + +void psched_ratecfg_precompute(struct psched_ratecfg *r, u32 rate) +{ + u64 factor; + u64 mult; + int shift; + + r->rate_bps = rate << 3; + r->shift = 0; + r->mult = 1; + /* + * Calibrate mult, shift so that token counting is accurate + * for smallest packet size (64 bytes). Token (time in ns) is + * computed as (bytes * 8) * NSEC_PER_SEC / rate_bps. It will + * work as long as the smallest packet transfer time can be + * accurately represented in nanosec. + */ + if (r->rate_bps > 0) { + /* + * Higher shift gives better accuracy. Find the largest + * shift such that mult fits in 32 bits. + */ + for (shift = 0; shift < 16; shift++) { + r->shift = shift; + factor = 8LLU * NSEC_PER_SEC * (1 << r->shift); + mult = div64_u64(factor, r->rate_bps); + if (mult > UINT_MAX) + break; + } + + r->shift = shift - 1; + factor = 8LLU * NSEC_PER_SEC * (1 << r->shift); + r->mult = div64_u64(factor, r->rate_bps); + } +} +EXPORT_SYMBOL(psched_ratecfg_precompute); |