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From: "Singh, Jasvinder" <jasvinder.singh@intel.com>
To: Stephen Hemminger <stephen@networkplumber.org>,
	"dev@dpdk.org" <dev@dpdk.org>
Cc: "Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>,
	"Wojciech Liguzinski" <wojciechx.liguzinski@intel.com>
Subject: RE: [PATCH v5 3/3] rte_pie: fix incorrect floating point math
Date: Tue, 21 Jun 2022 08:18:40 +0000	[thread overview]
Message-ID: <CY4PR11MB15890148C168FAC8A29B9569E0B39@CY4PR11MB1589.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20220526202653.99796-4-stephen@networkplumber.org>



> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Thursday, May 26, 2022 9:27 PM
> To: dev@dpdk.org
> Cc: Stephen Hemminger <stephen@networkplumber.org>; Dumitrescu,
> Cristian <cristian.dumitrescu@intel.com>; Singh, Jasvinder
> <jasvinder.singh@intel.com>; Wojciech Liguzinski
> <wojciechx.liguzinski@intel.com>
> Subject: [PATCH v5 3/3] rte_pie: fix incorrect floating point math
> 
> The function rte_pie_drop was attempting to do a random probability drop,
> but because of incorrect usage of fixed point divide it would always return 1.
> 
> Change to use new rte_drand() instead.
> 
> Fixes: 44c730b0e379 ("sched: add PIE based congestion management")
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  lib/sched/rte_pie.h | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/lib/sched/rte_pie.h b/lib/sched/rte_pie.h index
> 3e2c1ef46721..528f2ea878e8 100644
> --- a/lib/sched/rte_pie.h
> +++ b/lib/sched/rte_pie.h
> @@ -217,7 +217,6 @@ __rte_experimental
>  _rte_pie_drop(const struct rte_pie_config *pie_cfg,
>  	struct rte_pie *pie)
>  {
> -	uint64_t rand_value;
>  	uint64_t qdelay = pie_cfg->qdelay_ref / 2;
> 
>  	/* PIE is active but the queue is not congested: return 0 */ @@ -
> 240,9 +239,7 @@ _rte_pie_drop(const struct rte_pie_config *pie_cfg,
>  	if (pie->accu_prob >= 8.5)
>  		return 1;
> 
> -	rand_value = rte_rand()/RTE_RAND_MAX;
> -
> -	if ((double)rand_value < pie->drop_prob) {
> +	if (rte_drand() < pie->drop_prob) {
>  		pie->accu_prob = 0;
>  		return 1;
>  	}
> --
> 2.35.1


Acked-by: Jasvinder Singh <jasvinder.singh@intel.com>


  parent reply	other threads:[~2022-06-21  8:18 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-24 18:46 [RFT 0/2] pie: floating point fixes Stephen Hemminger
2022-05-24 18:46 ` [RFT 1/2] rte_pie: remove unnecessary floating point Stephen Hemminger
2022-05-24 18:46 ` [RFT 2/2] rte_pie: fix incorrect floating point math Stephen Hemminger
2022-05-24 19:31 ` [RFT 0/2] pie: floating point fixes Morten Brørup
2022-05-24 22:18 ` [RFT v2 0/3] pie: fix random number issues Stephen Hemminger
2022-05-24 22:18   ` [RFT v2 1/3] random: add rte_rand_float() Stephen Hemminger
2022-05-25 11:55     ` Ray Kinsella
2022-05-25 14:45     ` Mattias Rönnblom
2022-05-25 15:26       ` Morten Brørup
2022-05-25 15:45       ` Stephen Hemminger
2022-05-25 15:47       ` Stephen Hemminger
2022-05-24 22:18   ` [RFT v2 2/3] rte_pie: remove unnecessary floating point Stephen Hemminger
2022-05-24 22:18   ` [RFT v2 3/3] rte_pie: fix incorrect floating point math Stephen Hemminger
2022-05-25 17:12 ` [PATCH v3 0/3] introduce random floating point function Stephen Hemminger
2022-05-25 17:12   ` [PATCH v3 1/3] random: add rte_drand() funciton Stephen Hemminger
2022-05-25 17:12   ` [PATCH v3 2/3] rte_pie: remove unnecessary floating point Stephen Hemminger
2022-05-25 17:12   ` [PATCH v3 3/3] rte_pie: fix incorrect floating point math Stephen Hemminger
2022-05-25 20:31 ` [PATCH v4 0/3] introduce random floating point function Stephen Hemminger
2022-05-25 20:31   ` [PATCH v4 1/3] random: add rte_drand() function Stephen Hemminger
2022-05-26  9:56     ` Ray Kinsella
2022-05-26 13:20     ` Mattias Rönnblom
2022-05-26 15:25       ` Stephen Hemminger
2022-05-26 15:28       ` Stephen Hemminger
2022-05-26 20:19       ` Stephen Hemminger
2022-05-25 20:31   ` [PATCH v4 2/3] rte_pie: remove unnecessary floating point Stephen Hemminger
2022-05-25 20:31   ` [PATCH v4 3/3] rte_pie: fix incorrect floating point math Stephen Hemminger
2022-05-26  7:06   ` [PATCH v4 0/3] introduce random floating point function Morten Brørup
2022-05-26 20:26 ` [PATCH v5 " Stephen Hemminger
2022-05-26 20:26   ` [PATCH v5 1/3] random: add rte_drand() function Stephen Hemminger
2022-05-26 20:26   ` [PATCH v5 2/3] rte_pie: remove unnecessary floating point Stephen Hemminger
2022-05-30 11:50     ` Dumitrescu, Cristian
2022-06-21  8:18     ` Singh, Jasvinder
2022-05-26 20:26   ` [PATCH v5 3/3] rte_pie: fix incorrect floating point math Stephen Hemminger
2022-05-30 11:50     ` Dumitrescu, Cristian
2022-06-21  8:18     ` Singh, Jasvinder [this message]
2022-06-22  9:21   ` [PATCH v5 0/3] introduce random floating point function Thomas Monjalon

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