net: sched: pie: add more cases to auto-tune alpha and beta

The current implementation scales the local alpha and beta variables in the calculate_probability function by the same amount for all values of drop probability below 1%. RFC 8033 suggests using additional cases for auto-tuning alpha and beta when the drop probability is less than 1%. In order to add more auto-tuning cases, MAX_PROB must be scaled by u64 instead of u32 to prevent underflow when scaling the local alpha and beta variables in the calculate_probability function.

Mohit P. Tahiliani committed 7 years ago

Commit 3f7ae5f1 parent 30a92ad2 files · +33 −34Browse files

Showing the changes to include/uapi/linux (1 of 2 files). Show all

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include/uapi/linux/pkt_sched.h+1−1

@@ -954,7 +954,7 @@ enum { · 953 unmodified lines
954	954	#define TCA_PIE_MAX (__TCA_PIE_MAX - 1)
955	955
956	956	struct tc_pie_xstats {
957		− __u32 prob; /* current probability */
	957	+ __u64 prob; /* current probability */
958	958	__u32 delay; /* current delay in ms */
959	959	__u32 avg_dq_rate; /* current average dq_rate in bits/pie_time */
960	960	__u32 packets_in; /* total number of packets enqueued */