Traffic Control

Modules
	Queueing Classes
	Classifiers
	Queueing Disciplines

Macros
#define	RTNL_TC_RTABLE_SIZE   256
	Number of entries in a transmission time lookup table.

Enumerations
enum	rtnl_tc_stats_id {   RTNL_TC_PACKETS, RTNL_TC_BYTES, RTNL_TC_RATE_BPS, RTNL_TC_RATE_PPS,   RTNL_TC_QLEN, RTNL_TC_BACKLOG, RTNL_TC_DROPS, RTNL_TC_REQUEUES,   RTNL_TC_OVERLIMITS, __RTNL_TC_STATS_MAX }
	TC statistics identifiers. More...

Utilities
int	rtnl_tc_calc_txtime (int bufsize, int rate)
	Calculate time required to transmit buffer at a specific rate. More...
int	rtnl_tc_calc_bufsize (int txtime, int rate)
	Calculate buffer size able to transmit in a specific time and rate. More...
int	rtnl_tc_calc_cell_log (int cell_size)
	Calculate the binary logarithm for a specific cell size. More...

Rate Tables
int	rtnl_tc_build_rate_table (uint32_t *dst, uint8_t mpu, uint8_t overhead, int cell, int rate)
	Compute a transmission time lookup table. More...

Traffic Control Handle Translations
char *	rtnl_tc_handle2str (uint32_t handle, char *buf, size_t len)
	Convert a traffic control handle to a character string (Reentrant). More...
int	rtnl_tc_str2handle (const char *name, uint32_t *res)
	Convert a charactering strint to a traffic control handle. More...

Detailed Description

Enumeration Type Documentation

enum rtnl_tc_stats_id

Enumerator
RTNL_TC_PACKETS	Packets seen.
RTNL_TC_BYTES	Bytes seen.
RTNL_TC_RATE_BPS	Current bits/s (rate estimator)
RTNL_TC_RATE_PPS	Current packet/s (rate estimator)
RTNL_TC_QLEN	Queue length.
RTNL_TC_BACKLOG	Backlog length.
RTNL_TC_DROPS	Packets dropped.
RTNL_TC_REQUEUES	Number of requeues.
RTNL_TC_OVERLIMITS	Number of overlimits.

Definition at line 27 of file tc.h.

                      {
        RTNL_TC_PACKETS,        /**< Packets seen */
        RTNL_TC_BYTES,          /**< Bytes seen */
        RTNL_TC_RATE_BPS,       /**< Current bits/s (rate estimator) */
        RTNL_TC_RATE_PPS,       /**< Current packet/s (rate estimator) */
        RTNL_TC_QLEN,           /**< Queue length */
        RTNL_TC_BACKLOG,        /**< Backlog length */
        RTNL_TC_DROPS,          /**< Packets dropped */
        RTNL_TC_REQUEUES,       /**< Number of requeues */
        RTNL_TC_OVERLIMITS,     /**< Number of overlimits */
        __RTNL_TC_STATS_MAX,
};

Function Documentation

int rtnl_tc_calc_txtime	(	int	bufsize,
		int	rate
	)

Parameters

bufsize	Size of buffer to be transmited in bytes.
rate	Transmit rate in bytes per second.

Calculates the number of micro seconds required to transmit a specific buffer at a specific transmit rate.

Returns

Required transmit time in micro seconds.

Definition at line 383 of file tc.c.

Referenced by rtnl_qdisc_tbf_set_peakrate(), rtnl_qdisc_tbf_set_rate(), and rtnl_tc_build_rate_table().

{
        double tx_time_secs;
        
        tx_time_secs = (double) bufsize / (double) rate;

        return tx_time_secs * 1000000.;
}

int rtnl_tc_calc_bufsize	(	int	txtime,
		int	rate
	)

Parameters

txtime	Available transmit time in micro seconds.
rate	Transmit rate in bytes per second.

Calculates the size of the buffer that can be transmitted in a specific time period at a specific transmit rate.

Returns

Size of buffer in bytes.

Definition at line 406 of file tc.c.

{
        double bufsize;

        bufsize = (double) txtime * (double) rate;

        return bufsize / 1000000.;
}

int rtnl_tc_calc_cell_log

(

int

cell_size

)

Parameters

cell_size

Size of cell, must be a power of two.

Returns

Binary logirhtm of cell size or a negative error code.

Definition at line 420 of file tc.c.

Referenced by rtnl_tc_build_rate_table().

{
        int i;

        for (i = 0; i < 32; i++)
                if ((1 << i) == cell_size)
                        return i;

        return nl_errno(EINVAL);
}

int rtnl_tc_build_rate_table	(	uint32_t *	dst,
		uint8_t	mpu,
		uint8_t	overhead,
		int	cell,
		int	rate
	)

Parameters

dst	Destination buffer of RTNL_TC_RTABLE_SIZE uint32_t[].
mpu	Minimal size of a packet at all times.
overhead	Overhead to be added to each packet.
cell	Size of cell, i.e. size of step between entries in bytes.
rate	Rate in bytes per second.

Computes a table of RTNL_TC_RTABLE_SIZE entries specyfing the transmission times for various packet sizes, e.g. the transmission time for a packet of size pktsize could be looked up:

* txtime = table[pktsize >> log2(cell)];
* 

Definition at line 454 of file tc.c.

References rtnl_tc_calc_cell_log(), rtnl_tc_calc_txtime(), and RTNL_TC_RTABLE_SIZE.

{
        int i, size, cell_log;

        cell_log = rtnl_tc_calc_cell_log(cell);
        if (cell_log < 0)
                return cell_log;

        for (i = 0; i < RTNL_TC_RTABLE_SIZE; i++) {
                size = (i << cell_log) + overhead;
                if (size < mpu)
                        size = mpu;

                dst[i] = rtnl_tc_calc_txtime(size, rate);
        }

        return 0;
}

char* rtnl_tc_handle2str	(	uint32_t	handle,
		char *	buf,
		size_t	len
	)

Parameters

handle	traffic control handle
buf	destination buffer
len	buffer length

Converts a tarffic control handle to a character string in the form of MAJ:MIN and stores it in the specified destination buffer.

Returns

The destination buffer or the type encoded in hexidecimal form if no match was found.

Definition at line 493 of file tc.c.

{
        if (TC_H_ROOT == handle)
                snprintf(buf, len, "root");
        else if (TC_H_UNSPEC == handle)
                snprintf(buf, len, "none");
        else if (0 == TC_H_MAJ(handle))
                snprintf(buf, len, ":%02x", TC_H_MIN(handle));
        else if (0 == TC_H_MIN(handle))
                snprintf(buf, len, "%02x:", TC_H_MAJ(handle) >> 16);
        else
                snprintf(buf, len, "%02x:%02x",
                        TC_H_MAJ(handle) >> 16, TC_H_MIN(handle));

        return buf;
}

int rtnl_tc_str2handle	(	const char *	name,
		uint32_t *	res
	)

Parameters

name	traffic control handle as character string
res	destination buffer

Converts the provided character string specifying a traffic control handle to the corresponding numeric value.

The handle must be provided in one of the following formats:

• root
• none
• XXXX:
• :YYYY
• XXXX:YYYY
• XXXXYYYY

Returns

0 on success or a negative error code

Definition at line 528 of file tc.c.

{
        char *colon, *end;
        uint32_t h;

        if (!strcasecmp(name, "root")) {
                *res = TC_H_ROOT;
                return 0;
        }

        if (!strcasecmp(name, "none")) {
                *res = TC_H_UNSPEC;
                return 0;
        }

        h = strtoul(name, &colon, 16);

        if (colon == name) {
                /* :YYYY */
                h = 0;
                if (':' != *colon)
                        return -EINVAL;
        }

        if (':' == *colon) {
                /* check if we would lose bits */
                if (TC_H_MAJ(h))
                        return -ERANGE;
                h <<= 16;

                if ('\0' == colon[1]) {
                        /* XXXX: */
                        *res = h;
                } else {
                        /* XXXX:YYYY */
                        uint32_t l = strtoul(colon+1, &end, 16);

                        /* check if we overlap with major part */
                        if (TC_H_MAJ(l))
                                return -ERANGE;

                        if ('\0' != *end)
                                return -EINVAL;

                        *res = (h | l);
                }
        } else if ('\0' == *colon) {
                /* XXXXYYYY */
                *res = h;
        } else
                return -EINVAL;

        return 0;
}