pie: improve comments and commenting style
Improve the comments along with the commenting style used to describe the members of the structures and their initial values in the init functions. Signed-off-by: Mohit P. Tahiliani <tahiliani@nitk.edu.in> Signed-off-by: Leslie Monis <lesliemonis@gmail.com> Signed-off-by: Gautam Ramakrishnan <gautamramk@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -14,42 +14,74 @@
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#define DQCOUNT_INVALID -1
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#define PIE_SCALE 8
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/* parameters used */
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/**
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* struct pie_params - contains pie parameters
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* @target: target delay in pschedtime
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* @tudpate: interval at which drop probability is calculated
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* @limit: total number of packets that can be in the queue
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* @alpha: parameter to control drop probability
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* @beta: parameter to control drop probability
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* @ecn: is ECN marking of packets enabled
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* @bytemode: is drop probability scaled based on pkt size
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* @dq_rate_estimator: is Little's law used for qdelay calculation
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*/
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struct pie_params {
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psched_time_t target; /* user specified target delay in pschedtime */
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u32 tupdate; /* timer frequency (in jiffies) */
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u32 limit; /* number of packets that can be enqueued */
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u32 alpha; /* alpha and beta are between 0 and 32 */
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u32 beta; /* and are used for shift relative to 1 */
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u8 ecn; /* true if ecn is enabled */
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u8 bytemode; /* to scale drop early prob based on pkt size */
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u8 dq_rate_estimator; /* to calculate delay using Little's law */
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psched_time_t target;
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u32 tupdate;
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u32 limit;
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u32 alpha;
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u32 beta;
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u8 ecn;
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u8 bytemode;
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u8 dq_rate_estimator;
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};
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/* variables used */
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/**
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* struct pie_vars - contains pie variables
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* @qdelay: current queue delay
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* @qdelay_old: queue delay in previous qdelay calculation
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* @burst_time: burst time allowance
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* @dq_tstamp: timestamp at which dq rate was last calculated
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* @prob: drop probability
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* @accu_prob: accumulated drop probability
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* @dq_count: number of bytes dequeued in a measurement cycle
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* @avg_dq_rate: calculated average dq rate
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* @qlen_old: queue length during previous qdelay calculation
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* @accu_prob_overflows: number of times accu_prob overflows
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*/
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struct pie_vars {
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psched_time_t qdelay;
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psched_time_t qdelay_old;
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psched_time_t burst_time;
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psched_time_t dq_tstamp; /* drain rate */
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u64 prob; /* probability but scaled by u64 limit. */
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u64 accu_prob; /* accumulated drop probability */
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u64 dq_count; /* measured in bytes */
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u32 avg_dq_rate; /* bytes per pschedtime tick,scaled */
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u32 qlen_old; /* in bytes */
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u8 accu_prob_overflows; /* overflows of accu_prob */
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psched_time_t dq_tstamp;
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u64 prob;
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u64 accu_prob;
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u64 dq_count;
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u32 avg_dq_rate;
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u32 qlen_old;
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u8 accu_prob_overflows;
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};
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/* statistics gathering */
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/**
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* struct pie_stats - contains pie stats
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* @packets_in: total number of packets enqueued
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* @dropped: packets dropped due to pie action
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* @overlimit: packets dropped due to lack of space in queue
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* @ecn_mark: packets marked with ECN
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* @maxq: maximum queue size
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*/
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struct pie_stats {
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u32 packets_in; /* total number of packets enqueued */
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u32 dropped; /* packets dropped due to pie_action */
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u32 overlimit; /* dropped due to lack of space in queue */
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u32 ecn_mark; /* packets marked with ECN */
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u32 maxq; /* maximum queue size */
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u32 packets_in;
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u32 dropped;
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u32 overlimit;
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u32 ecn_mark;
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u32 maxq;
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};
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/* private skb vars */
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/**
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* struct pie_skb_cb - contains private skb vars
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* @enqueue_time: timestamp when the packet is enqueued
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*/
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struct pie_skb_cb {
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psched_time_t enqueue_time;
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};
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@ -58,7 +90,7 @@ static inline void pie_params_init(struct pie_params *params)
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{
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params->target = PSCHED_NS2TICKS(15 * NSEC_PER_MSEC); /* 15 ms */
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params->tupdate = usecs_to_jiffies(15 * USEC_PER_MSEC); /* 15 ms */
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params->limit = 1000; /* default of 1000 packets */
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params->limit = 1000;
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params->alpha = 2;
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params->beta = 20;
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params->ecn = false;
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@ -68,8 +100,7 @@ static inline void pie_params_init(struct pie_params *params)
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static inline void pie_vars_init(struct pie_vars *vars)
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{
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/* default of 150 ms in pschedtime */
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vars->burst_time = PSCHED_NS2TICKS(150 * NSEC_PER_MSEC);
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vars->burst_time = PSCHED_NS2TICKS(150 * NSEC_PER_MSEC); /* 150 ms */
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vars->dq_tstamp = DTIME_INVALID;
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vars->accu_prob = 0;
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vars->dq_count = DQCOUNT_INVALID;
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