Commit b42a3d7c authored by Mohit P. Tahiliani's avatar Mohit P. Tahiliani Committed by David S. Miller

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: default avatarMohit P. Tahiliani <tahiliani@nitk.edu.in>
Signed-off-by: default avatarLeslie Monis <lesliemonis@gmail.com>
Signed-off-by: default avatarGautam Ramakrishnan <gautamramk@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2dfb1952
...@@ -14,42 +14,74 @@ ...@@ -14,42 +14,74 @@
#define DQCOUNT_INVALID -1 #define DQCOUNT_INVALID -1
#define PIE_SCALE 8 #define PIE_SCALE 8
/* parameters used */ /**
* struct pie_params - contains pie parameters
* @target: target delay in pschedtime
* @tudpate: interval at which drop probability is calculated
* @limit: total number of packets that can be in the queue
* @alpha: parameter to control drop probability
* @beta: parameter to control drop probability
* @ecn: is ECN marking of packets enabled
* @bytemode: is drop probability scaled based on pkt size
* @dq_rate_estimator: is Little's law used for qdelay calculation
*/
struct pie_params { struct pie_params {
psched_time_t target; /* user specified target delay in pschedtime */ psched_time_t target;
u32 tupdate; /* timer frequency (in jiffies) */ u32 tupdate;
u32 limit; /* number of packets that can be enqueued */ u32 limit;
u32 alpha; /* alpha and beta are between 0 and 32 */ u32 alpha;
u32 beta; /* and are used for shift relative to 1 */ u32 beta;
u8 ecn; /* true if ecn is enabled */ u8 ecn;
u8 bytemode; /* to scale drop early prob based on pkt size */ u8 bytemode;
u8 dq_rate_estimator; /* to calculate delay using Little's law */ u8 dq_rate_estimator;
}; };
/* variables used */ /**
* struct pie_vars - contains pie variables
* @qdelay: current queue delay
* @qdelay_old: queue delay in previous qdelay calculation
* @burst_time: burst time allowance
* @dq_tstamp: timestamp at which dq rate was last calculated
* @prob: drop probability
* @accu_prob: accumulated drop probability
* @dq_count: number of bytes dequeued in a measurement cycle
* @avg_dq_rate: calculated average dq rate
* @qlen_old: queue length during previous qdelay calculation
* @accu_prob_overflows: number of times accu_prob overflows
*/
struct pie_vars { struct pie_vars {
psched_time_t qdelay; psched_time_t qdelay;
psched_time_t qdelay_old; psched_time_t qdelay_old;
psched_time_t burst_time; psched_time_t burst_time;
psched_time_t dq_tstamp; /* drain rate */ psched_time_t dq_tstamp;
u64 prob; /* probability but scaled by u64 limit. */ u64 prob;
u64 accu_prob; /* accumulated drop probability */ u64 accu_prob;
u64 dq_count; /* measured in bytes */ u64 dq_count;
u32 avg_dq_rate; /* bytes per pschedtime tick,scaled */ u32 avg_dq_rate;
u32 qlen_old; /* in bytes */ u32 qlen_old;
u8 accu_prob_overflows; /* overflows of accu_prob */ u8 accu_prob_overflows;
}; };
/* statistics gathering */ /**
* struct pie_stats - contains pie stats
* @packets_in: total number of packets enqueued
* @dropped: packets dropped due to pie action
* @overlimit: packets dropped due to lack of space in queue
* @ecn_mark: packets marked with ECN
* @maxq: maximum queue size
*/
struct pie_stats { struct pie_stats {
u32 packets_in; /* total number of packets enqueued */ u32 packets_in;
u32 dropped; /* packets dropped due to pie_action */ u32 dropped;
u32 overlimit; /* dropped due to lack of space in queue */ u32 overlimit;
u32 ecn_mark; /* packets marked with ECN */ u32 ecn_mark;
u32 maxq; /* maximum queue size */ u32 maxq;
}; };
/* private skb vars */ /**
* struct pie_skb_cb - contains private skb vars
* @enqueue_time: timestamp when the packet is enqueued
*/
struct pie_skb_cb { struct pie_skb_cb {
psched_time_t enqueue_time; psched_time_t enqueue_time;
}; };
...@@ -58,7 +90,7 @@ static inline void pie_params_init(struct pie_params *params) ...@@ -58,7 +90,7 @@ static inline void pie_params_init(struct pie_params *params)
{ {
params->target = PSCHED_NS2TICKS(15 * NSEC_PER_MSEC); /* 15 ms */ params->target = PSCHED_NS2TICKS(15 * NSEC_PER_MSEC); /* 15 ms */
params->tupdate = usecs_to_jiffies(15 * USEC_PER_MSEC); /* 15 ms */ params->tupdate = usecs_to_jiffies(15 * USEC_PER_MSEC); /* 15 ms */
params->limit = 1000; /* default of 1000 packets */ params->limit = 1000;
params->alpha = 2; params->alpha = 2;
params->beta = 20; params->beta = 20;
params->ecn = false; params->ecn = false;
...@@ -68,8 +100,7 @@ static inline void pie_params_init(struct pie_params *params) ...@@ -68,8 +100,7 @@ static inline void pie_params_init(struct pie_params *params)
static inline void pie_vars_init(struct pie_vars *vars) static inline void pie_vars_init(struct pie_vars *vars)
{ {
/* default of 150 ms in pschedtime */ vars->burst_time = PSCHED_NS2TICKS(150 * NSEC_PER_MSEC); /* 150 ms */
vars->burst_time = PSCHED_NS2TICKS(150 * NSEC_PER_MSEC);
vars->dq_tstamp = DTIME_INVALID; vars->dq_tstamp = DTIME_INVALID;
vars->accu_prob = 0; vars->accu_prob = 0;
vars->dq_count = DQCOUNT_INVALID; vars->dq_count = DQCOUNT_INVALID;
......
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