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authorLeslie Monis <lesliemonis@gmail.com>2020-03-04 19:56:01 +0100
committerDavid S. Miller <davem@davemloft.net>2020-03-04 22:25:55 +0100
commit105e808c1da2a2827a4a374ae6e3003249729eec (patch)
treee6045369559f0fb426929d5fee0e22303a7d95e7 /include/net/pie.h
parentpie: remove unnecessary type casting (diff)
downloadlinux-105e808c1da2a2827a4a374ae6e3003249729eec.tar.xz
linux-105e808c1da2a2827a4a374ae6e3003249729eec.zip
pie: remove pie_vars->accu_prob_overflows
The variable pie_vars->accu_prob is used as an accumulator for probability values. Since probabilty values are scaled using the MAX_PROB macro denoting (2^64 - 1), pie_vars->accu_prob is likely to overflow as it is of type u64. The variable pie_vars->accu_prob_overflows counts the number of times the variable pie_vars->accu_prob overflows. The MAX_PROB macro needs to be equal to at least (2^39 - 1) in order to do precise calculations without any underflow. Thus MAX_PROB can be reduced to (2^56 - 1) without affecting the precision in calculations drastically. Doing so will eliminate the need for the variable pie_vars->accu_prob_overflows as the variable pie_vars->accu_prob will never overflow. Removing the variable pie_vars->accu_prob_overflows also reduces the size of the structure pie_vars to exactly 64 bytes. Signed-off-by: Mohit P. Tahiliani <tahiliani@nitk.edu.in> Signed-off-by: Gautam Ramakrishnan <gautamramk@gmail.com> Signed-off-by: Leslie Monis <lesliemonis@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/pie.h')
-rw-r--r--include/net/pie.h5
1 files changed, 1 insertions, 4 deletions
diff --git a/include/net/pie.h b/include/net/pie.h
index 24f68c1e9919..1c645b76a2ed 100644
--- a/include/net/pie.h
+++ b/include/net/pie.h
@@ -8,7 +8,7 @@
#include <net/inet_ecn.h>
#include <net/pkt_sched.h>
-#define MAX_PROB U64_MAX
+#define MAX_PROB (U64_MAX >> BITS_PER_BYTE)
#define DTIME_INVALID U64_MAX
#define QUEUE_THRESHOLD 16384
#define DQCOUNT_INVALID -1
@@ -47,7 +47,6 @@ struct pie_params {
* @dq_count: number of bytes dequeued in a measurement cycle
* @avg_dq_rate: calculated average dq rate
* @backlog_old: queue backlog during previous qdelay calculation
- * @accu_prob_overflows: number of times accu_prob overflows
*/
struct pie_vars {
psched_time_t qdelay;
@@ -59,7 +58,6 @@ struct pie_vars {
u64 dq_count;
u32 avg_dq_rate;
u32 backlog_old;
- u8 accu_prob_overflows;
};
/**
@@ -107,7 +105,6 @@ static inline void pie_vars_init(struct pie_vars *vars)
vars->accu_prob = 0;
vars->dq_count = DQCOUNT_INVALID;
vars->avg_dq_rate = 0;
- vars->accu_prob_overflows = 0;
}
static inline struct pie_skb_cb *get_pie_cb(const struct sk_buff *skb)