* [PATCH net v5 0/2] net: sched: fix some issues
@ 2013-12-05 7:10 Yang Yingliang
2013-12-05 7:10 ` [PATCH net v5 1/2] net: sched: tbf: fix calculation of max_size Yang Yingliang
2013-12-05 7:10 ` [PATCH net v5 2/2] net: sched: htb: fix calculation of quantum Yang Yingliang
0 siblings, 2 replies; 9+ messages in thread
From: Yang Yingliang @ 2013-12-05 7:10 UTC (permalink / raw)
To: davem, netdev; +Cc: eric.dumazet, brouer, jpirko, jbrouer
fix calculation of max_size in tbf
fix quantum calculation introduced by 64bit rates.
v2
patch 1/2: redescribe the regression.
patch 2/2: add Eric's ack.
v3
patch 1/2: use psched_l2t_ns to calculate max_size
and cleanup exit/done section suggested by Jesper.
v4
patch 1/2:
1.Update commit message suggested by Jesper.
2.Use a macro to replace 65535 constant.
3.Add condition that when peakrate is lower than rate, return -EINVAL.
4.Don't use cell_log anymore.
v5
patch 1/2:
1.Remove rtab and ptab use suggested by Eric.
2.Don't reduce max_size to 65536, as Eric suggested that
if a burst set to 200KB, we do not want tbf use 64KB
or even less. So add a helper psched_ns_t2l to calculate
max_size directly.
Yang Yingliang (2):
net: sched: tbf: fix calculation of max_size
net: sched: htb: fix calculation of quantum
include/net/sch_generic.h | 46 ++++++++++++++++++++++++++++
net/sched/sch_htb.c | 18 ++++++-----
net/sched/sch_tbf.c | 76 ++++++++++++++++++++---------------------------
3 files changed, 89 insertions(+), 51 deletions(-)
--
1.8.0
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH net v5 1/2] net: sched: tbf: fix calculation of max_size
2013-12-05 7:10 [PATCH net v5 0/2] net: sched: fix some issues Yang Yingliang
@ 2013-12-05 7:10 ` Yang Yingliang
2013-12-05 12:15 ` Eric Dumazet
2013-12-05 7:10 ` [PATCH net v5 2/2] net: sched: htb: fix calculation of quantum Yang Yingliang
1 sibling, 1 reply; 9+ messages in thread
From: Yang Yingliang @ 2013-12-05 7:10 UTC (permalink / raw)
To: davem, netdev; +Cc: eric.dumazet, brouer, jpirko, jbrouer
Current max_size is caluated from rate table. Now, the rate table
has been replaced and it's wrong to caculate max_size based on this
rate table. It can lead wrong calculation of max_size.
The burst in kernel may be lower than user asked, because burst may gets
some loss when transform it to buffer(E.g. "burst 40kb rate 30mbit/s")
and it seems we cannot avoid this loss. Burst's value(max_size) based on
rate table may be equal user asked. If a packet's length is max_size, this
packet will be stalled in tbf_dequeue() because its length is above the
burst in kernel so that it cannot get enough tokens. The max_size guards
against enqueuing packet sizes above q->buffer "time" in tbf_enqueue().
To make consistent with the calculation of tokens, this patch add a helper
psched_ns_t2l() to calculate burst(max_size) directly to fix this problem.
After this fix, we can support to using 64bit rates to calculate burst as well.
Suggested-by: Jesper Dangaard Brouer <jbrouer@redhat•com>
Suggested-by: Eric Dumazet <edumazet@google•com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei•com>
---
include/net/sch_generic.h | 46 ++++++++++++++++++++++++++++
net/sched/sch_tbf.c | 76 ++++++++++++++++++++---------------------------
2 files changed, 79 insertions(+), 43 deletions(-)
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index d0a6321..8da64f3 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -701,6 +701,52 @@ static inline u64 psched_l2t_ns(const struct psched_ratecfg *r,
return ((u64)len * r->mult) >> r->shift;
}
+/* Time to Length, convert time in ns to length in bytes
+ * to determinate how many bytes can be sent in given time.
+ */
+static inline u64 psched_ns_t2l(const struct psched_ratecfg *r,
+ u64 time_in_ns)
+{
+ u64 len = time_in_ns;
+ u8 shift = r->shift;
+ bool is_div = false;
+
+ /* The formula is :
+ * len = (time_in_ns << shift) / mult
+ * when time_in_ns does shift, it would overflow.
+ * If overflow happens first time, do division.
+ * Then do shift. If it happens again,
+ * set lenth to ~0ULL.
+ */
+ while (shift) {
+ if (len & (1ULL << 63)) {
+ if (!is_div) {
+ len = div64_u64(len, r->mult);
+ is_div = true;
+ } else {
+ /* overflow happens */
+ len = ~0ULL;
+ is_div = true;
+ break;
+ }
+ }
+ len <<= 1;
+ shift--;
+ }
+ if (!is_div)
+ len = div64_u64(len, r->mult);
+
+ if (unlikely(r->linklayer == TC_LINKLAYER_ATM))
+ len = (len / 53) * 48;
+
+ if (len > r->overhead)
+ len -= r->overhead;
+ else
+ len = 0;
+
+ return len;
+}
+
void psched_ratecfg_precompute(struct psched_ratecfg *r,
const struct tc_ratespec *conf,
u64 rate64);
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index a609005..2dd7cea 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -289,10 +289,8 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
struct tbf_sched_data *q = qdisc_priv(sch);
struct nlattr *tb[TCA_TBF_MAX + 1];
struct tc_tbf_qopt *qopt;
- struct qdisc_rate_table *rtab = NULL;
- struct qdisc_rate_table *ptab = NULL;
struct Qdisc *child = NULL;
- int max_size, n;
+ u64 max_size;
u64 rate64 = 0, prate64 = 0;
err = nla_parse_nested(tb, TCA_TBF_MAX, opt, tbf_policy);
@@ -304,38 +302,13 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
goto done;
qopt = nla_data(tb[TCA_TBF_PARMS]);
- rtab = qdisc_get_rtab(&qopt->rate, tb[TCA_TBF_RTAB]);
- if (rtab == NULL)
- goto done;
-
- if (qopt->peakrate.rate) {
- if (qopt->peakrate.rate > qopt->rate.rate)
- ptab = qdisc_get_rtab(&qopt->peakrate, tb[TCA_TBF_PTAB]);
- if (ptab == NULL)
- goto done;
- }
-
- for (n = 0; n < 256; n++)
- if (rtab->data[n] > qopt->buffer)
- break;
- max_size = (n << qopt->rate.cell_log) - 1;
- if (ptab) {
- int size;
-
- for (n = 0; n < 256; n++)
- if (ptab->data[n] > qopt->mtu)
- break;
- size = (n << qopt->peakrate.cell_log) - 1;
- if (size < max_size)
- max_size = size;
- }
- if (max_size < 0)
- goto done;
+ if (qopt->rate.linklayer == TC_LINKLAYER_UNAWARE)
+ qdisc_put_rtab(qdisc_get_rtab(&qopt->rate,
+ tb[TCA_TBF_RTAB]));
- if (max_size < psched_mtu(qdisc_dev(sch)))
- pr_warn_ratelimited("sch_tbf: burst %u is lower than device %s mtu (%u) !\n",
- max_size, qdisc_dev(sch)->name,
- psched_mtu(qdisc_dev(sch)));
+ if (qopt->peakrate.linklayer == TC_LINKLAYER_UNAWARE)
+ qdisc_put_rtab(qdisc_get_rtab(&qopt->peakrate,
+ tb[TCA_TBF_PTAB]));
if (q->qdisc != &noop_qdisc) {
err = fifo_set_limit(q->qdisc, qopt->limit);
@@ -357,30 +330,47 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
}
q->limit = qopt->limit;
q->mtu = PSCHED_TICKS2NS(qopt->mtu);
- q->max_size = max_size;
q->buffer = PSCHED_TICKS2NS(qopt->buffer);
q->tokens = q->buffer;
q->ptokens = q->mtu;
if (tb[TCA_TBF_RATE64])
rate64 = nla_get_u64(tb[TCA_TBF_RATE64]);
- psched_ratecfg_precompute(&q->rate, &rtab->rate, rate64);
- if (ptab) {
+ psched_ratecfg_precompute(&q->rate, &qopt->rate, rate64);
+ if (!q->rate.rate_bytes_ps)
+ goto unlock_done;
+
+ max_size = min_t(u64, psched_ns_t2l(&q->rate, q->buffer), ~0U);
+
+ if (qopt->peakrate.rate) {
if (tb[TCA_TBF_PRATE64])
prate64 = nla_get_u64(tb[TCA_TBF_PRATE64]);
- psched_ratecfg_precompute(&q->peak, &ptab->rate, prate64);
+ psched_ratecfg_precompute(&q->peak, &qopt->peakrate, prate64);
+ if (q->peak.rate_bytes_ps <= q->rate.rate_bytes_ps) {
+ pr_err("Peakrate must be higher than rate!\n");
+ goto unlock_done;
+ }
+
+ max_size = min_t(u64, max_size, psched_ns_t2l(&q->peak, q->mtu));
q->peak_present = true;
} else {
q->peak_present = false;
}
+ if (max_size < psched_mtu(qdisc_dev(sch)))
+ pr_warn_ratelimited("sch_tbf: burst %llu is lower than device %s mtu (%u) !\n",
+ max_size, qdisc_dev(sch)->name,
+ psched_mtu(qdisc_dev(sch)));
+
+ q->max_size = max_size;
+
+ sch_tree_unlock(sch);
+ return 0;
+
+unlock_done:
sch_tree_unlock(sch);
- err = 0;
+ err = -EINVAL;
done:
- if (rtab)
- qdisc_put_rtab(rtab);
- if (ptab)
- qdisc_put_rtab(ptab);
return err;
}
--
1.8.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH net v5 2/2] net: sched: htb: fix calculation of quantum
2013-12-05 7:10 [PATCH net v5 0/2] net: sched: fix some issues Yang Yingliang
2013-12-05 7:10 ` [PATCH net v5 1/2] net: sched: tbf: fix calculation of max_size Yang Yingliang
@ 2013-12-05 7:10 ` Yang Yingliang
2013-12-05 12:18 ` Eric Dumazet
1 sibling, 1 reply; 9+ messages in thread
From: Yang Yingliang @ 2013-12-05 7:10 UTC (permalink / raw)
To: davem, netdev; +Cc: eric.dumazet, brouer, jpirko, jbrouer
Now, 32bit rates may be not the true rate.
So use rate_bytes_ps which is from
max(rate32, rate64) to calcualte quantum.
Signed-off-by: Yang Yingliang <yangyingliang@huawei•com>
Acked-by: Eric Dumazet <edumazet@google•com>
---
net/sched/sch_htb.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 0e1e38b..57c6678 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1477,11 +1477,20 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
sch_tree_lock(sch);
}
+ rate64 = tb[TCA_HTB_RATE64] ? nla_get_u64(tb[TCA_HTB_RATE64]) : 0;
+
+ ceil64 = tb[TCA_HTB_CEIL64] ? nla_get_u64(tb[TCA_HTB_CEIL64]) : 0;
+
+ psched_ratecfg_precompute(&cl->rate, &hopt->rate, rate64);
+ psched_ratecfg_precompute(&cl->ceil, &hopt->ceil, ceil64);
+
/* it used to be a nasty bug here, we have to check that node
* is really leaf before changing cl->un.leaf !
*/
if (!cl->level) {
- cl->quantum = hopt->rate.rate / q->rate2quantum;
+ u64 quantum = div64_u64(cl->rate.rate_bytes_ps,
+ q->rate2quantum);
+ cl->quantum = min_t(u64, quantum, INT_MAX);
if (!hopt->quantum && cl->quantum < 1000) {
pr_warning(
"HTB: quantum of class %X is small. Consider r2q change.\n",
@@ -1500,13 +1509,6 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
cl->prio = TC_HTB_NUMPRIO - 1;
}
- rate64 = tb[TCA_HTB_RATE64] ? nla_get_u64(tb[TCA_HTB_RATE64]) : 0;
-
- ceil64 = tb[TCA_HTB_CEIL64] ? nla_get_u64(tb[TCA_HTB_CEIL64]) : 0;
-
- psched_ratecfg_precompute(&cl->rate, &hopt->rate, rate64);
- psched_ratecfg_precompute(&cl->ceil, &hopt->ceil, ceil64);
-
cl->buffer = PSCHED_TICKS2NS(hopt->buffer);
cl->cbuffer = PSCHED_TICKS2NS(hopt->cbuffer);
--
1.8.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH net v5 1/2] net: sched: tbf: fix calculation of max_size
2013-12-05 7:10 ` [PATCH net v5 1/2] net: sched: tbf: fix calculation of max_size Yang Yingliang
@ 2013-12-05 12:15 ` Eric Dumazet
2013-12-06 2:24 ` Yang Yingliang
0 siblings, 1 reply; 9+ messages in thread
From: Eric Dumazet @ 2013-12-05 12:15 UTC (permalink / raw)
To: Yang Yingliang; +Cc: davem, netdev, brouer, jpirko, jbrouer
On Thu, 2013-12-05 at 15:10 +0800, Yang Yingliang wrote:
> Current max_size is caluated from rate table. Now, the rate table
> has been replaced and it's wrong to caculate max_size based on this
> rate table. It can lead wrong calculation of max_size.
>
> The burst in kernel may be lower than user asked, because burst may gets
> some loss when transform it to buffer(E.g. "burst 40kb rate 30mbit/s")
> and it seems we cannot avoid this loss. Burst's value(max_size) based on
> rate table may be equal user asked. If a packet's length is max_size, this
> packet will be stalled in tbf_dequeue() because its length is above the
> burst in kernel so that it cannot get enough tokens. The max_size guards
> against enqueuing packet sizes above q->buffer "time" in tbf_enqueue().
>
> To make consistent with the calculation of tokens, this patch add a helper
> psched_ns_t2l() to calculate burst(max_size) directly to fix this problem.
>
> After this fix, we can support to using 64bit rates to calculate burst as well.
>
> Suggested-by: Jesper Dangaard Brouer <jbrouer@redhat•com>
> Suggested-by: Eric Dumazet <edumazet@google•com>
No, I did not suggest this patch.
> Signed-off-by: Yang Yingliang <yangyingliang@huawei•com>
> ---
> include/net/sch_generic.h | 46 ++++++++++++++++++++++++++++
> net/sched/sch_tbf.c | 76 ++++++++++++++++++++---------------------------
> 2 files changed, 79 insertions(+), 43 deletions(-)
>
> diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
> index d0a6321..8da64f3 100644
> --- a/include/net/sch_generic.h
> +++ b/include/net/sch_generic.h
> @@ -701,6 +701,52 @@ static inline u64 psched_l2t_ns(const struct psched_ratecfg *r,
> return ((u64)len * r->mult) >> r->shift;
> }
>
> +/* Time to Length, convert time in ns to length in bytes
> + * to determinate how many bytes can be sent in given time.
> + */
> +static inline u64 psched_ns_t2l(const struct psched_ratecfg *r,
> + u64 time_in_ns)
inline ?
Really ?
This is management path, there is no point inlining this.
> +{
> + u64 len = time_in_ns;
> + u8 shift = r->shift;
> + bool is_div = false;
> +
> + /* The formula is :
> + * len = (time_in_ns << shift) / mult
> + * when time_in_ns does shift, it would overflow.
> + * If overflow happens first time, do division.
> + * Then do shift. If it happens again,
> + * set lenth to ~0ULL.
> + */
> + while (shift) {
> + if (len & (1ULL << 63)) {
> + if (!is_div) {
> + len = div64_u64(len, r->mult);
> + is_div = true;
> + } else {
> + /* overflow happens */
> + len = ~0ULL;
> + is_div = true;
> + break;
> + }
> + }
> + len <<= 1;
> + shift--;
> + }
> + if (!is_div)
> + len = div64_u64(len, r->mult);
Thats terrible.
Given that the intended formula was :
time_in_ns = (NSEC_PER_SEC * len) / rate_bps;
This translates to following optimal C code
u64 len = time_in_ns * r->rate_bytes_ps;
do_div(len, NSEC_PER_SEC);
Why do you use r->shift and r->mult which are optimized for the reverse
operation in fast path (no divide), I do not know.
> + max_size = min_t(u64, psched_ns_t2l(&q->rate, q->buffer), ~0U);
> +
> + if (qopt->peakrate.rate) {
> if (tb[TCA_TBF_PRATE64])
> prate64 = nla_get_u64(tb[TCA_TBF_PRATE64]);
> - psched_ratecfg_precompute(&q->peak, &ptab->rate, prate64);
> + psched_ratecfg_precompute(&q->peak, &qopt->peakrate, prate64);
> + if (q->peak.rate_bytes_ps <= q->rate.rate_bytes_ps) {
> + pr_err("Peakrate must be higher than rate!\n");
Do not add messages like that without rate limiting them.
Plus there is no context, we know nothing.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH net v5 2/2] net: sched: htb: fix calculation of quantum
2013-12-05 7:10 ` [PATCH net v5 2/2] net: sched: htb: fix calculation of quantum Yang Yingliang
@ 2013-12-05 12:18 ` Eric Dumazet
2013-12-06 2:36 ` Yang Yingliang
0 siblings, 1 reply; 9+ messages in thread
From: Eric Dumazet @ 2013-12-05 12:18 UTC (permalink / raw)
To: Yang Yingliang; +Cc: davem, netdev, brouer, jpirko, jbrouer
On Thu, 2013-12-05 at 15:10 +0800, Yang Yingliang wrote:
> Now, 32bit rates may be not the true rate.
> So use rate_bytes_ps which is from
> max(rate32, rate64) to calcualte quantum.
>
> Signed-off-by: Yang Yingliang <yangyingliang@huawei•com>
> Acked-by: Eric Dumazet <edumazet@google•com>
> ---
> net/sched/sch_htb.c | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
> index 0e1e38b..57c6678 100644
> --- a/net/sched/sch_htb.c
> +++ b/net/sched/sch_htb.c
> @@ -1477,11 +1477,20 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
> sch_tree_lock(sch);
> }
>
> + rate64 = tb[TCA_HTB_RATE64] ? nla_get_u64(tb[TCA_HTB_RATE64]) : 0;
> +
> + ceil64 = tb[TCA_HTB_CEIL64] ? nla_get_u64(tb[TCA_HTB_CEIL64]) : 0;
> +
> + psched_ratecfg_precompute(&cl->rate, &hopt->rate, rate64);
> + psched_ratecfg_precompute(&cl->ceil, &hopt->ceil, ceil64);
> +
> /* it used to be a nasty bug here, we have to check that node
> * is really leaf before changing cl->un.leaf !
> */
> if (!cl->level) {
> - cl->quantum = hopt->rate.rate / q->rate2quantum;
> + u64 quantum = div64_u64(cl->rate.rate_bytes_ps,
> + q->rate2quantum);
q->rate2quantum being 32bit, prefer the following :
u64 quantum = cl->rate.rate_bytes_ps;
do_div(quantum, q->rate2quantum);
Since it maps to better assembly code on 32bit arches.
> + cl->quantum = min_t(u64, quantum, INT_MAX);
> if (!hopt->quantum && cl->quantum < 1000) {
> pr_warning(
> "HTB: quantum of class %X is small. Consider r2q change.\n",
> @@ -1500,13 +1509,6 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
> cl->prio = TC_HTB_NUMPRIO - 1;
> }
>
> - rate64 = tb[TCA_HTB_RATE64] ? nla_get_u64(tb[TCA_HTB_RATE64]) : 0;
> -
> - ceil64 = tb[TCA_HTB_CEIL64] ? nla_get_u64(tb[TCA_HTB_CEIL64]) : 0;
> -
> - psched_ratecfg_precompute(&cl->rate, &hopt->rate, rate64);
> - psched_ratecfg_precompute(&cl->ceil, &hopt->ceil, ceil64);
> -
> cl->buffer = PSCHED_TICKS2NS(hopt->buffer);
> cl->cbuffer = PSCHED_TICKS2NS(hopt->cbuffer);
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH net v5 1/2] net: sched: tbf: fix calculation of max_size
2013-12-05 12:15 ` Eric Dumazet
@ 2013-12-06 2:24 ` Yang Yingliang
2013-12-06 3:46 ` Eric Dumazet
0 siblings, 1 reply; 9+ messages in thread
From: Yang Yingliang @ 2013-12-06 2:24 UTC (permalink / raw)
To: Eric Dumazet; +Cc: davem, netdev, brouer, jpirko, jbrouer
Hi, Eric
Thanks for your reviewing and advice!
On 2013/12/5 20:15, Eric Dumazet wrote:
> On Thu, 2013-12-05 at 15:10 +0800, Yang Yingliang wrote:
>>
>> Suggested-by: Jesper Dangaard Brouer <jbrouer@redhat•com>
>> Suggested-by: Eric Dumazet <edumazet@google•com>
>
> No, I did not suggest this patch.
You suggested that
if (qopt->rate.linklayer == TC_LINKLAYER_UNAWARE)
qdisc_put_rtab(qdisc_get_rtab(&qopt->rate,
tb[TCA_TBF_RTAB]));
so I added your suggestion.
>
>> Signed-off-by: Yang Yingliang <yangyingliang@huawei•com>
>> ---
>> include/net/sch_generic.h | 46 ++++++++++++++++++++++++++++
>> net/sched/sch_tbf.c | 76 ++++++++++++++++++++---------------------------
>> 2 files changed, 79 insertions(+), 43 deletions(-)
>>
>> diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
>> index d0a6321..8da64f3 100644
>> --- a/include/net/sch_generic.h
>> +++ b/include/net/sch_generic.h
>> @@ -701,6 +701,52 @@ static inline u64 psched_l2t_ns(const struct psched_ratecfg *r,
>> return ((u64)len * r->mult) >> r->shift;
>> }
>>
>> +/* Time to Length, convert time in ns to length in bytes
>> + * to determinate how many bytes can be sent in given time.
>> + */
>> +static inline u64 psched_ns_t2l(const struct psched_ratecfg *r,
>> + u64 time_in_ns)
>
> inline ?
>
> Really ?
>
> This is management path, there is no point inlining this.
>
>> +{
>> + u64 len = time_in_ns;
>> + u8 shift = r->shift;
>> + bool is_div = false;
>> +
>> + /* The formula is :
>> + * len = (time_in_ns << shift) / mult
>> + * when time_in_ns does shift, it would overflow.
>> + * If overflow happens first time, do division.
>> + * Then do shift. If it happens again,
>> + * set lenth to ~0ULL.
>> + */
>> + while (shift) {
>> + if (len & (1ULL << 63)) {
>> + if (!is_div) {
>> + len = div64_u64(len, r->mult);
>> + is_div = true;
>> + } else {
>> + /* overflow happens */
>> + len = ~0ULL;
>> + is_div = true;
>> + break;
>> + }
>> + }
>> + len <<= 1;
>> + shift--;
>> + }
>> + if (!is_div)
>> + len = div64_u64(len, r->mult);
>
> Thats terrible.
>
> Given that the intended formula was :
>
> time_in_ns = (NSEC_PER_SEC * len) / rate_bps;
>
> This translates to following optimal C code
>
> u64 len = time_in_ns * r->rate_bytes_ps;
> do_div(len, NSEC_PER_SEC);
>
> Why do you use r->shift and r->mult which are optimized for the reverse
> operation in fast path (no divide), I do not know.
The formula to calculate tokens is :
(len * r->mult) >> r->shift
so I tried to use r->shift and r->mult to calculate the len.
Your way looks better, I'll change it in v6.
>
>> + max_size = min_t(u64, psched_ns_t2l(&q->rate, q->buffer), ~0U);
>> +
>> + if (qopt->peakrate.rate) {
>> if (tb[TCA_TBF_PRATE64])
>> prate64 = nla_get_u64(tb[TCA_TBF_PRATE64]);
>> - psched_ratecfg_precompute(&q->peak, &ptab->rate, prate64);
>> + psched_ratecfg_precompute(&q->peak, &qopt->peakrate, prate64);
>> + if (q->peak.rate_bytes_ps <= q->rate.rate_bytes_ps) {
>> + pr_err("Peakrate must be higher than rate!\n");
>
> Do not add messages like that without rate limiting them.
>
> Plus there is no context, we know nothing.
OK, I'll use pr_warn_ratelimited instead.
Regards,
Yang
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH net v5 2/2] net: sched: htb: fix calculation of quantum
2013-12-05 12:18 ` Eric Dumazet
@ 2013-12-06 2:36 ` Yang Yingliang
0 siblings, 0 replies; 9+ messages in thread
From: Yang Yingliang @ 2013-12-06 2:36 UTC (permalink / raw)
To: Eric Dumazet; +Cc: davem, netdev, brouer, jpirko, jbrouer
On 2013/12/5 20:18, Eric Dumazet wrote:
> On Thu, 2013-12-05 at 15:10 +0800, Yang Yingliang wrote:
>> if (!cl->level) {
>> - cl->quantum = hopt->rate.rate / q->rate2quantum;
>> + u64 quantum = div64_u64(cl->rate.rate_bytes_ps,
>> + q->rate2quantum);
>
> q->rate2quantum being 32bit, prefer the following :
>
> u64 quantum = cl->rate.rate_bytes_ps;
>
> do_div(quantum, q->rate2quantum);
>
> Since it maps to better assembly code on 32bit arches.
Change it in v6, thanks!
Regards,
Yang
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH net v5 1/2] net: sched: tbf: fix calculation of max_size
2013-12-06 2:24 ` Yang Yingliang
@ 2013-12-06 3:46 ` Eric Dumazet
2013-12-06 3:57 ` Yang Yingliang
0 siblings, 1 reply; 9+ messages in thread
From: Eric Dumazet @ 2013-12-06 3:46 UTC (permalink / raw)
To: Yang Yingliang; +Cc: davem, netdev, brouer, jpirko, jbrouer
On Fri, 2013-12-06 at 10:24 +0800, Yang Yingliang wrote:
> Hi, Eric
> Thanks for your reviewing and advice!
>
> On 2013/12/5 20:15, Eric Dumazet wrote:
> > On Thu, 2013-12-05 at 15:10 +0800, Yang Yingliang wrote:
> >>
> >> Suggested-by: Jesper Dangaard Brouer <jbrouer@redhat•com>
> >> Suggested-by: Eric Dumazet <edumazet@google•com>
> >
> > No, I did not suggest this patch.
>
> You suggested that
>
> if (qopt->rate.linklayer == TC_LINKLAYER_UNAWARE)
> qdisc_put_rtab(qdisc_get_rtab(&qopt->rate,
> tb[TCA_TBF_RTAB]));
>
> so I added your suggestion.
OK : The exact meaning of 'Suggested-by: XX' is :
1) the patch idea was given by XX.
2) Then you implemented it.
This is not really the case here : You had the idea of this patch.
I made some feedbacks, you have no special tag to add for that.
Later, if I agree with your next patch set I'll add my own
"Acked-by: ..."
If not (for example I am slow to respond and it got merged), its not a
big deal.
Thanks
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH net v5 1/2] net: sched: tbf: fix calculation of max_size
2013-12-06 3:46 ` Eric Dumazet
@ 2013-12-06 3:57 ` Yang Yingliang
0 siblings, 0 replies; 9+ messages in thread
From: Yang Yingliang @ 2013-12-06 3:57 UTC (permalink / raw)
To: Eric Dumazet; +Cc: davem, netdev, brouer, jpirko, jbrouer
On 2013/12/6 11:46, Eric Dumazet wrote:
> On Fri, 2013-12-06 at 10:24 +0800, Yang Yingliang wrote:
>> Hi, Eric
>> Thanks for your reviewing and advice!
>>
>> On 2013/12/5 20:15, Eric Dumazet wrote:
>>> On Thu, 2013-12-05 at 15:10 +0800, Yang Yingliang wrote:
>>>>
>>>> Suggested-by: Jesper Dangaard Brouer <jbrouer@redhat•com>
>>>> Suggested-by: Eric Dumazet <edumazet@google•com>
>>>
>>> No, I did not suggest this patch.
>>
>> You suggested that
>>
>> if (qopt->rate.linklayer == TC_LINKLAYER_UNAWARE)
>> qdisc_put_rtab(qdisc_get_rtab(&qopt->rate,
>> tb[TCA_TBF_RTAB]));
>>
>> so I added your suggestion.
>
> OK : The exact meaning of 'Suggested-by: XX' is :
>
> 1) the patch idea was given by XX.
> 2) Then you implemented it.
>
> This is not really the case here : You had the idea of this patch.
>
> I made some feedbacks, you have no special tag to add for that.
>
> Later, if I agree with your next patch set I'll add my own
> "Acked-by: ..."
>
> If not (for example I am slow to respond and it got merged), its not a
> big deal.
>
> Thanks
>
Got it.
Thanks for your explanation!
>
>
>
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2013-12-06 3:59 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-12-05 7:10 [PATCH net v5 0/2] net: sched: fix some issues Yang Yingliang
2013-12-05 7:10 ` [PATCH net v5 1/2] net: sched: tbf: fix calculation of max_size Yang Yingliang
2013-12-05 12:15 ` Eric Dumazet
2013-12-06 2:24 ` Yang Yingliang
2013-12-06 3:46 ` Eric Dumazet
2013-12-06 3:57 ` Yang Yingliang
2013-12-05 7:10 ` [PATCH net v5 2/2] net: sched: htb: fix calculation of quantum Yang Yingliang
2013-12-05 12:18 ` Eric Dumazet
2013-12-06 2:36 ` Yang Yingliang
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