Hello,
first, sorry, I thought I had already taken your patch but
apparently not.
On Wed, Nov 12, 2025 at 05:47:34PM -0000, Jacques Heunis (BLOOMBERG/ LONDON)
wrote:
> All of the other bandwidth-limiting code stores limits and intermediate
> (byte) counters as unsigned integers.
> (...)
> This is a niche possibility, because it requires that a bandwidth limit is
> defined in the range [2^31, 2^32). In this case, the raw limit value would
> not fit into a signed integer, and close to the end of the period, the
> `(elapsed * freq)/period` calculation could produce a value which also
> doesn't fit into a signed integer.
(...)
Yes, you're totally right. I'm just having one (minor) issue, your
mailer has completely mangled spaces in your patch as you can see below.
I can try to reproduce it manually since it's not very long, but if
you still have it, could you please send it as an attachment ? Generally
mails that are broken for inline don't modify attachments.
thank you!
Willy
> include/haproxy/freq_ctr.h | 2 +-
> src/flt_bwlim.c | 4 ++--
> src/freq_ctr.c | 19 ++++++++++++-------
> 3 files changed, 15 insertions(+), 10 deletions(-)
>
> diff --git a/include/haproxy/freq_ctr.h b/include/haproxy/freq_ctr.h
> index 6ddcde842..dfb187483 100644
> --- a/include/haproxy/freq_ctr.h
> +++ b/include/haproxy/freq_ctr.h
> @@ -31,7 +31,7 @@
> ullong _freq_ctr_total_from_values(uint period, int pend, uint tick, ullong
> past, ullong curr);
> ullong freq_ctr_total(const struct freq_ctr *ctr, uint period, int pend);
> ullong freq_ctr_total_estimate(const struct freq_ctr *ctr, uint period, int
> pend);
> -int freq_ctr_overshoot_period(const struct freq_ctr *ctr, uint period, uint
> freq);
> +uint freq_ctr_overshoot_period(const struct freq_ctr *ctr, uint period, uint
> freq);
> uint update_freq_ctr_period_slow(struct freq_ctr *ctr, uint period, uint inc);
>
> /* Only usable during single threaded startup phase. */
> diff --git a/src/flt_bwlim.c b/src/flt_bwlim.c
> index 3c75b9bb0..40a876790 100644
> --- a/src/flt_bwlim.c
> +++ b/src/flt_bwlim.c
> @@ -79,9 +79,9 @@ static int bwlim_apply_limit(struct filter *filter, struct
> channel *chn, unsigne
> struct bwlim_state *st = filter->ctx;
> struct freq_ctr *bytes_rate;
> uint64_t remain;
> - unsigned int period, limit, tokens, users, factor;
> + unsigned int period, limit, tokens, users, factor, overshoot;
> unsigned int wait = 0;
> - int overshoot, ret = 0;
> + int ret = 0;
>
> /* Don't forward anything if there is nothing to forward or the waiting
> * time is not expired
> diff --git a/src/freq_ctr.c b/src/freq_ctr.c
> index 7f9e346de..571798297 100644
> --- a/src/freq_ctr.c
> +++ b/src/freq_ctr.c
> @@ -184,17 +184,17 @@ ullong freq_ctr_total_estimate(const struct freq_ctr
> *ctr, uint period, int pend
> return _freq_ctr_total_from_values(period, pend, tick, past, curr);
> }
>
> -/* Returns the excess of events (may be negative) over the current period for
> - * target frequency <freq>. It returns 0 if the counter is in the future or
> if
> - * the counter is empty. The result considers the position of the current
> time
> - * within the current period.
> +/* Returns the excess of events over the current period for target frequency
> + * <freq>. It returns 0 if the counter is in the future or if the counter is
> + * empty. The result considers the position of the current time within the
> + * current period.
> *
> * The caller may safely add new events if result is negative or null.
> */
> -int freq_ctr_overshoot_period(const struct freq_ctr *ctr, uint period, uint
> freq)
> +uint freq_ctr_overshoot_period(const struct freq_ctr *ctr, uint period, uint
> freq)
> {
> ullong curr, old_curr;
> - uint tick, old_tick;
> + uint tick, old_tick, linear_usage;
> int elapsed;
>
> tick = HA_ATOMIC_LOAD(&ctr->curr_tick);
> @@ -245,7 +245,12 @@ int freq_ctr_overshoot_period(const struct freq_ctr
> *ctr, uint period, uint freq
> return 0;
> }
>
> - return curr - div64_32((uint64_t)elapsed * freq, period);
> + linear_usage = div64_32((uint64_t)elapsed * freq, period);
> + if (curr < linear_usage) {
> + /* The counter is below a uniform linear increase across the period, no
> overshoot */
> + return 0;
> + }
> + return curr - linear_usage;
> }
>
> /*
> --
> 2.43.0
>
