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mac80211: Tx frame latency statistics
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Measure TX latency and jitter statistics per station per TID.
These Measurements are disabled by default and can be enabled
via debugfs.

Features included for each station's TID:

1. Keep count of the maximum and average latency of Tx frames.
2. Keep track of many frames arrived in a specific time range
   (need to enable through debugfs and configure the bins ranges)

Signed-off-by: Matti Gottlieb <[email protected]>
Signed-off-by: Johannes Berg <[email protected]>
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@mattigot @jmberg-intel
mattigot authored and jmberg-intel committed Dec 2, 2013
1 parent 1d940aa commit ad38bfc
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Showing 8 changed files with 486 additions and 0 deletions.
168 changes: 168 additions & 0 deletions net/mac80211/debugfs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,172 @@

#define DEBUGFS_FORMAT_BUFFER_SIZE 100

#define TX_LATENCY_BIN_DELIMTER_C ','
#define TX_LATENCY_BIN_DELIMTER_S ","
#define TX_LATENCY_BINS_DISABLED "enable(bins disabled)\n"
#define TX_LATENCY_DISABLED "disable\n"


/*
* Display if Tx latency statistics & bins are enabled/disabled
*/
static ssize_t sta_tx_latency_stat_read(struct file *file,
char __user *userbuf,
size_t count, loff_t *ppos)
{
struct ieee80211_local *local = file->private_data;
struct ieee80211_tx_latency_bin_ranges *tx_latency;
char *buf;
int bufsz, i, ret;
int pos = 0;

rcu_read_lock();

tx_latency = rcu_dereference(local->tx_latency);

if (tx_latency && tx_latency->n_ranges) {
bufsz = tx_latency->n_ranges * 15;
buf = kzalloc(bufsz, GFP_ATOMIC);
if (!buf)
goto err;

for (i = 0; i < tx_latency->n_ranges; i++)
pos += scnprintf(buf + pos, bufsz - pos, "%d,",
tx_latency->ranges[i]);
pos += scnprintf(buf + pos, bufsz - pos, "\n");
} else if (tx_latency) {
bufsz = sizeof(TX_LATENCY_BINS_DISABLED) + 1;
buf = kzalloc(bufsz, GFP_ATOMIC);
if (!buf)
goto err;

pos += scnprintf(buf + pos, bufsz - pos, "%s\n",
TX_LATENCY_BINS_DISABLED);
} else {
bufsz = sizeof(TX_LATENCY_DISABLED) + 1;
buf = kzalloc(bufsz, GFP_ATOMIC);
if (!buf)
goto err;

pos += scnprintf(buf + pos, bufsz - pos, "%s\n",
TX_LATENCY_DISABLED);
}

rcu_read_unlock();

ret = simple_read_from_buffer(userbuf, count, ppos, buf, pos);
kfree(buf);

return ret;
err:
rcu_read_unlock();
return -ENOMEM;
}

/*
* Receive input from user regarding Tx latency statistics
* The input should indicate if Tx latency statistics and bins are
* enabled/disabled.
* If bins are enabled input should indicate the amount of different bins and
* their ranges. Each bin will count how many Tx frames transmitted within the
* appropriate latency.
* Legal input is:
* a) "enable(bins disabled)" - to enable only general statistics
* b) "a,b,c,d,...z" - to enable general statistics and bins, where all are
* numbers and a < b < c < d.. < z
* c) "disable" - disable all statistics
* NOTE: must configure Tx latency statistics bins before stations connected.
*/

static ssize_t sta_tx_latency_stat_write(struct file *file,
const char __user *userbuf,
size_t count, loff_t *ppos)
{
struct ieee80211_local *local = file->private_data;
char buf[128] = {};
char *bins = buf;
char *token;
int buf_size, i, alloc_size;
int prev_bin = 0;
int n_ranges = 0;
int ret = count;
struct ieee80211_tx_latency_bin_ranges *tx_latency;

if (sizeof(buf) <= count)
return -EINVAL;
buf_size = count;
if (copy_from_user(buf, userbuf, buf_size))
return -EFAULT;

mutex_lock(&local->sta_mtx);

/* cannot change config once we have stations */
if (local->num_sta)
goto unlock;

tx_latency =
rcu_dereference_protected(local->tx_latency,
lockdep_is_held(&local->sta_mtx));

/* disable Tx statistics */
if (!strcmp(buf, TX_LATENCY_DISABLED)) {
if (!tx_latency)
goto unlock;
rcu_assign_pointer(local->tx_latency, NULL);
synchronize_rcu();
kfree(tx_latency);
goto unlock;
}

/* Tx latency already enabled */
if (tx_latency)
goto unlock;

if (strcmp(TX_LATENCY_BINS_DISABLED, buf)) {
/* check how many bins and between what ranges user requested */
token = buf;
while (*token != '\0') {
if (*token == TX_LATENCY_BIN_DELIMTER_C)
n_ranges++;
token++;
}
n_ranges++;
}

alloc_size = sizeof(struct ieee80211_tx_latency_bin_ranges) +
n_ranges * sizeof(u32);
tx_latency = kzalloc(alloc_size, GFP_ATOMIC);
if (!tx_latency) {
ret = -ENOMEM;
goto unlock;
}
tx_latency->n_ranges = n_ranges;
for (i = 0; i < n_ranges; i++) { /* setting bin ranges */
token = strsep(&bins, TX_LATENCY_BIN_DELIMTER_S);
sscanf(token, "%d", &tx_latency->ranges[i]);
/* bins values should be in ascending order */
if (prev_bin >= tx_latency->ranges[i]) {
ret = -EINVAL;
kfree(tx_latency);
goto unlock;
}
prev_bin = tx_latency->ranges[i];
}
rcu_assign_pointer(local->tx_latency, tx_latency);

unlock:
mutex_unlock(&local->sta_mtx);

return ret;
}

static const struct file_operations stats_tx_latency_ops = {
.write = sta_tx_latency_stat_write,
.read = sta_tx_latency_stat_read,
.open = simple_open,
.llseek = generic_file_llseek,
};

int mac80211_format_buffer(char __user *userbuf, size_t count,
loff_t *ppos, char *fmt, ...)
{
Expand Down Expand Up @@ -315,4 +481,6 @@ void debugfs_hw_add(struct ieee80211_local *local)
DEBUGFS_DEVSTATS_ADD(dot11RTSFailureCount);
DEBUGFS_DEVSTATS_ADD(dot11FCSErrorCount);
DEBUGFS_DEVSTATS_ADD(dot11RTSSuccessCount);

DEBUGFS_DEVSTATS_ADD(tx_latency);
}
134 changes: 134 additions & 0 deletions net/mac80211/debugfs_sta.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,13 @@ static const struct file_operations sta_ ##name## _ops = { \
.llseek = generic_file_llseek, \
}

#define STA_OPS_W(name) \
static const struct file_operations sta_ ##name## _ops = { \
.write = sta_##name##_write, \
.open = simple_open, \
.llseek = generic_file_llseek, \
}

#define STA_OPS_RW(name) \
static const struct file_operations sta_ ##name## _ops = { \
.read = sta_##name##_read, \
Expand Down Expand Up @@ -388,6 +395,131 @@ static ssize_t sta_last_rx_rate_read(struct file *file, char __user *userbuf,
}
STA_OPS(last_rx_rate);

static int
sta_tx_latency_stat_header(struct ieee80211_tx_latency_bin_ranges *tx_latency,
char *buf, int pos, int bufsz)
{
int i;
int range_count = tx_latency->n_ranges;
u32 *bin_ranges = tx_latency->ranges;

pos += scnprintf(buf + pos, bufsz - pos,
"Station\t\t\tTID\tMax\tAvg");
if (range_count) {
pos += scnprintf(buf + pos, bufsz - pos,
"\t<=%d", bin_ranges[0]);
for (i = 0; i < range_count - 1; i++)
pos += scnprintf(buf + pos, bufsz - pos, "\t%d-%d",
bin_ranges[i], bin_ranges[i+1]);
pos += scnprintf(buf + pos, bufsz - pos,
"\t%d<", bin_ranges[range_count - 1]);
}

pos += scnprintf(buf + pos, bufsz - pos, "\n");

return pos;
}

static int
sta_tx_latency_stat_table(struct ieee80211_tx_latency_bin_ranges *tx_lat_range,
struct ieee80211_tx_latency_stat *tx_lat,
char *buf, int pos, int bufsz, int tid)
{
u32 avg = 0;
int j;
int bin_count = tx_lat->bin_count;

pos += scnprintf(buf + pos, bufsz - pos, "\t\t\t%d", tid);
/* make sure you don't divide in 0 */
if (tx_lat->counter)
avg = tx_lat->sum / tx_lat->counter;

pos += scnprintf(buf + pos, bufsz - pos, "\t%d\t%d",
tx_lat->max, avg);

if (tx_lat_range->n_ranges && tx_lat->bins)
for (j = 0; j < bin_count; j++)
pos += scnprintf(buf + pos, bufsz - pos,
"\t%d", tx_lat->bins[j]);
pos += scnprintf(buf + pos, bufsz - pos, "\n");

return pos;
}

/*
* Output Tx latency statistics station && restart all statistics information
*/
static ssize_t sta_tx_latency_stat_read(struct file *file,
char __user *userbuf,
size_t count, loff_t *ppos)
{
struct sta_info *sta = file->private_data;
struct ieee80211_local *local = sta->local;
struct ieee80211_tx_latency_bin_ranges *tx_latency;
char *buf;
int bufsz, ret, i;
int pos = 0;

bufsz = 20 * IEEE80211_NUM_TIDS *
sizeof(struct ieee80211_tx_latency_stat);
buf = kzalloc(bufsz, GFP_KERNEL);
if (!buf)
return -ENOMEM;

rcu_read_lock();

tx_latency = rcu_dereference(local->tx_latency);

if (!sta->tx_lat) {
pos += scnprintf(buf + pos, bufsz - pos,
"Tx latency statistics are not enabled\n");
goto unlock;
}

pos = sta_tx_latency_stat_header(tx_latency, buf, pos, bufsz);

pos += scnprintf(buf + pos, bufsz - pos, "%pM\n", sta->sta.addr);
for (i = 0; i < IEEE80211_NUM_TIDS; i++)
pos = sta_tx_latency_stat_table(tx_latency, &sta->tx_lat[i],
buf, pos, bufsz, i);
unlock:
rcu_read_unlock();

ret = simple_read_from_buffer(userbuf, count, ppos, buf, pos);
kfree(buf);

return ret;
}
STA_OPS(tx_latency_stat);

static ssize_t sta_tx_latency_stat_reset_write(struct file *file,
const char __user *userbuf,
size_t count, loff_t *ppos)
{
u32 *bins;
int bin_count;
struct sta_info *sta = file->private_data;
int i;

if (!sta->tx_lat)
return -EINVAL;

for (i = 0; i < IEEE80211_NUM_TIDS; i++) {
bins = sta->tx_lat[i].bins;
bin_count = sta->tx_lat[i].bin_count;

sta->tx_lat[i].max = 0;
sta->tx_lat[i].sum = 0;
sta->tx_lat[i].counter = 0;

if (bin_count)
memset(bins, 0, bin_count * sizeof(u32));
}

return count;
}
STA_OPS_W(tx_latency_stat_reset);

#define DEBUGFS_ADD(name) \
debugfs_create_file(#name, 0400, \
sta->debugfs.dir, sta, &sta_ ##name## _ops);
Expand Down Expand Up @@ -441,6 +573,8 @@ void ieee80211_sta_debugfs_add(struct sta_info *sta)
DEBUGFS_ADD(last_ack_signal);
DEBUGFS_ADD(current_tx_rate);
DEBUGFS_ADD(last_rx_rate);
DEBUGFS_ADD(tx_latency_stat);
DEBUGFS_ADD(tx_latency_stat_reset);

DEBUGFS_ADD_COUNTER(rx_packets, rx_packets);
DEBUGFS_ADD_COUNTER(tx_packets, tx_packets);
Expand Down
24 changes: 24 additions & 0 deletions net/mac80211/ieee80211_i.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -898,6 +898,24 @@ struct tpt_led_trigger {
};
#endif

/*
* struct ieee80211_tx_latency_bin_ranges - Tx latency statistics bins ranges
*
* Measuring Tx latency statistics. Counts how many Tx frames transmitted in a
* certain latency range (in Milliseconds). Each station that uses these
* ranges will have bins to count the amount of frames received in that range.
* The user can configure the ranges via debugfs.
* If ranges is NULL then Tx latency statistics bins are disabled for all
* stations.
*
* @n_ranges: number of ranges that are taken in account
* @ranges: the ranges that the user requested or NULL if disabled.
*/
struct ieee80211_tx_latency_bin_ranges {
int n_ranges;
u32 ranges[];
};

/**
* mac80211 scan flags - currently active scan mode
*
Expand Down Expand Up @@ -1050,6 +1068,12 @@ struct ieee80211_local {
struct timer_list sta_cleanup;
int sta_generation;

/*
* Tx latency statistics parameters for all stations.
* Can enable via debugfs (NULL when disabled).
*/
struct ieee80211_tx_latency_bin_ranges __rcu *tx_latency;

struct sk_buff_head pending[IEEE80211_MAX_QUEUES];
struct tasklet_struct tx_pending_tasklet;

Expand Down
2 changes: 2 additions & 0 deletions net/mac80211/main.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1142,6 +1142,8 @@ void ieee80211_free_hw(struct ieee80211_hw *hw)
ieee80211_free_ack_frame, NULL);
idr_destroy(&local->ack_status_frames);

kfree(rcu_access_pointer(local->tx_latency));

wiphy_free(local->hw.wiphy);
}
EXPORT_SYMBOL(ieee80211_free_hw);
Expand Down
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