Re: [dpdk-dev] [PATCH] sched: make RED scaling configurable

["Kantecki, Tomasz" <tomasz.kantecki@intel.com>]

Hi Alan,

This looks like a very good idea but I think the patch must also cover adequate changes of test/test/test_red.c file.
What range of fraction/max_threshold values did you find to work correctly with no further code mods?

Thanks,
Tomasz

-----Original Message-----
From: alangordondewar@gmail.com [mailto:alangordondewar@gmail.com] 
Sent: Friday, September 1, 2017 2:42 PM
To: Kantecki, Tomasz <tomasz.kantecki@intel.com>
Cc: dev@dpdk.org; Alan Dewar <alan.dewar@att.com>
Subject: [PATCH] sched: make RED scaling configurable

From: Alan Dewar <alan.dewar@att.com>

The RED code stores the maximum threshold is a 32-bit integer as a pseudo fixed-point floating number with 10 fractional bits.  Twelve other bits are used to encode the filter weight, leaving just 10 bits for the queue length.  This limits the maximum queue length supported by RED queues as 1024 packets.

Move the "hard" definitions from red.h into config/common_base so that RED scaling can be configured during build.

Signed-off-by: Alan Dewar <alan.dewar@att.com>
---
 config/common_base         | 2 ++
 lib/librte_sched/rte_red.h | 3 +--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/config/common_base b/config/common_base index 5e97a08..5501dfe 100644
--- a/config/common_base
+++ b/config/common_base
@@ -666,6 +666,8 @@ CONFIG_RTE_SCHED_COLLECT_STATS=n  CONFIG_RTE_SCHED_SUBPORT_TC_OV=n
 CONFIG_RTE_SCHED_PORT_N_GRINDERS=8
 CONFIG_RTE_SCHED_VECTOR=n
+CONFIG_RTE_RED_SCALING=10
+CONFIG_RTE_RED_MAX_TH_MAX=1023
 
 #
 # Compile the distributor library
diff --git a/lib/librte_sched/rte_red.h b/lib/librte_sched/rte_red.h index ca12227..49d3379 100644
--- a/lib/librte_sched/rte_red.h
+++ b/lib/librte_sched/rte_red.h
@@ -51,10 +51,9 @@ extern "C" {
 #include <rte_debug.h>
 #include <rte_cycles.h>
 #include <rte_branch_prediction.h>
+#include <rte_config.h>
 
-#define RTE_RED_SCALING                     10         /**< Fraction size for fixed-point */
 #define RTE_RED_S                           (1 << 22)  /**< Packet size multiplied by number of leaf queues */
-#define RTE_RED_MAX_TH_MAX                  1023       /**< Max threshold limit in fixed point format */
 #define RTE_RED_WQ_LOG2_MIN                 1          /**< Min inverse filter weight value */
 #define RTE_RED_WQ_LOG2_MAX                 12         /**< Max inverse filter weight value */
 #define RTE_RED_MAXP_INV_MIN                1          /**< Min inverse mark probability value */
--
2.1.4

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