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bql: Byte queue limits
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Networking stack support for byte queue limits, uses dynamic queue
limits library.  Byte queue limits are maintained per transmit queue,
and a dql structure has been added to netdev_queue structure for this
purpose.

Configuration of bql is in the tx-<n> sysfs directory for the queue
under the byte_queue_limits directory.  Configuration includes:
limit_min, bql minimum limit
limit_max, bql maximum limit
hold_time, bql slack hold time

Also under the directory are:
limit, current byte limit
inflight, current number of bytes on the queue

Signed-off-by: Tom Herbert <[email protected]>
Acked-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@davem330
Tom Herbert authored and davem330 committed Nov 29, 2011
1 parent 927fbec commit 114cf58
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Showing 4 changed files with 172 additions and 9 deletions.
32 changes: 31 additions & 1 deletion include/linux/netdevice.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,7 @@
#include <linux/rculist.h>
#include <linux/dmaengine.h>
#include <linux/workqueue.h>
#include <linux/dynamic_queue_limits.h>

#include <linux/ethtool.h>
#include <net/net_namespace.h>
Expand Down Expand Up @@ -541,7 +542,6 @@ struct netdev_queue {
*/
struct net_device *dev;
struct Qdisc *qdisc;
unsigned long state;
struct Qdisc *qdisc_sleeping;
#ifdef CONFIG_SYSFS
struct kobject kobj;
Expand All @@ -564,6 +564,12 @@ struct netdev_queue {
* (/sys/class/net/DEV/Q/trans_timeout)
*/
unsigned long trans_timeout;

unsigned long state;

#ifdef CONFIG_BQL
struct dql dql;
#endif
} ____cacheline_aligned_in_smp;

static inline int netdev_queue_numa_node_read(const struct netdev_queue *q)
Expand Down Expand Up @@ -1862,6 +1868,15 @@ static inline int netif_xmit_frozen_or_stopped(const struct netdev_queue *dev_qu
static inline void netdev_tx_sent_queue(struct netdev_queue *dev_queue,
unsigned int bytes)
{
#ifdef CONFIG_BQL
dql_queued(&dev_queue->dql, bytes);
if (unlikely(dql_avail(&dev_queue->dql) < 0)) {
set_bit(__QUEUE_STATE_STACK_XOFF, &dev_queue->state);
if (unlikely(dql_avail(&dev_queue->dql) >= 0))
clear_bit(__QUEUE_STATE_STACK_XOFF,
&dev_queue->state);
}
#endif
}

static inline void netdev_sent_queue(struct net_device *dev, unsigned int bytes)
Expand All @@ -1872,6 +1887,18 @@ static inline void netdev_sent_queue(struct net_device *dev, unsigned int bytes)
static inline void netdev_tx_completed_queue(struct netdev_queue *dev_queue,
unsigned pkts, unsigned bytes)
{
#ifdef CONFIG_BQL
if (likely(bytes)) {
dql_completed(&dev_queue->dql, bytes);
if (unlikely(test_bit(__QUEUE_STATE_STACK_XOFF,
&dev_queue->state) &&
dql_avail(&dev_queue->dql) >= 0)) {
if (test_and_clear_bit(__QUEUE_STATE_STACK_XOFF,
&dev_queue->state))
netif_schedule_queue(dev_queue);
}
}
#endif
}

static inline void netdev_completed_queue(struct net_device *dev,
Expand All @@ -1882,6 +1909,9 @@ static inline void netdev_completed_queue(struct net_device *dev,

static inline void netdev_tx_reset_queue(struct netdev_queue *q)
{
#ifdef CONFIG_BQL
dql_reset(&q->dql);
#endif
}

static inline void netdev_reset_queue(struct net_device *dev_queue)
Expand Down
6 changes: 6 additions & 0 deletions net/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -239,6 +239,12 @@ config NETPRIO_CGROUP
Cgroup subsystem for use in assigning processes to network priorities on
a per-interface basis

config BQL
boolean
depends on SYSFS
select DQL
default y

config HAVE_BPF_JIT
bool

Expand Down
3 changes: 3 additions & 0 deletions net/core/dev.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5470,6 +5470,9 @@ static void netdev_init_one_queue(struct net_device *dev,
queue->xmit_lock_owner = -1;
netdev_queue_numa_node_write(queue, NUMA_NO_NODE);
queue->dev = dev;
#ifdef CONFIG_BQL
dql_init(&queue->dql, HZ);
#endif
}

static int netif_alloc_netdev_queues(struct net_device *dev)
Expand Down
140 changes: 132 additions & 8 deletions net/core/net-sysfs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
#include <linux/wireless.h>
#include <linux/vmalloc.h>
#include <linux/export.h>
#include <linux/jiffies.h>
#include <net/wext.h>

#include "net-sysfs.h"
Expand Down Expand Up @@ -845,6 +846,116 @@ static ssize_t show_trans_timeout(struct netdev_queue *queue,
static struct netdev_queue_attribute queue_trans_timeout =
__ATTR(tx_timeout, S_IRUGO, show_trans_timeout, NULL);

#ifdef CONFIG_BQL
/*
* Byte queue limits sysfs structures and functions.
*/
static ssize_t bql_show(char *buf, unsigned int value)
{
return sprintf(buf, "%u\n", value);
}

static ssize_t bql_set(const char *buf, const size_t count,
unsigned int *pvalue)
{
unsigned int value;
int err;

if (!strcmp(buf, "max") || !strcmp(buf, "max\n"))
value = DQL_MAX_LIMIT;
else {
err = kstrtouint(buf, 10, &value);
if (err < 0)
return err;
if (value > DQL_MAX_LIMIT)
return -EINVAL;
}

*pvalue = value;

return count;
}

static ssize_t bql_show_hold_time(struct netdev_queue *queue,
struct netdev_queue_attribute *attr,
char *buf)
{
struct dql *dql = &queue->dql;

return sprintf(buf, "%u\n", jiffies_to_msecs(dql->slack_hold_time));
}

static ssize_t bql_set_hold_time(struct netdev_queue *queue,
struct netdev_queue_attribute *attribute,
const char *buf, size_t len)
{
struct dql *dql = &queue->dql;
unsigned value;
int err;

err = kstrtouint(buf, 10, &value);
if (err < 0)
return err;

dql->slack_hold_time = msecs_to_jiffies(value);

return len;
}

static struct netdev_queue_attribute bql_hold_time_attribute =
__ATTR(hold_time, S_IRUGO | S_IWUSR, bql_show_hold_time,
bql_set_hold_time);

static ssize_t bql_show_inflight(struct netdev_queue *queue,
struct netdev_queue_attribute *attr,
char *buf)
{
struct dql *dql = &queue->dql;

return sprintf(buf, "%u\n", dql->num_queued - dql->num_completed);
}

static struct netdev_queue_attribute bql_inflight_attribute =
__ATTR(inflight, S_IRUGO | S_IWUSR, bql_show_inflight, NULL);

#define BQL_ATTR(NAME, FIELD) \
static ssize_t bql_show_ ## NAME(struct netdev_queue *queue, \
struct netdev_queue_attribute *attr, \
char *buf) \
{ \
return bql_show(buf, queue->dql.FIELD); \
} \
\
static ssize_t bql_set_ ## NAME(struct netdev_queue *queue, \
struct netdev_queue_attribute *attr, \
const char *buf, size_t len) \
{ \
return bql_set(buf, len, &queue->dql.FIELD); \
} \
\
static struct netdev_queue_attribute bql_ ## NAME ## _attribute = \
__ATTR(NAME, S_IRUGO | S_IWUSR, bql_show_ ## NAME, \
bql_set_ ## NAME);

BQL_ATTR(limit, limit)
BQL_ATTR(limit_max, max_limit)
BQL_ATTR(limit_min, min_limit)

static struct attribute *dql_attrs[] = {
&bql_limit_attribute.attr,
&bql_limit_max_attribute.attr,
&bql_limit_min_attribute.attr,
&bql_hold_time_attribute.attr,
&bql_inflight_attribute.attr,
NULL
};

static struct attribute_group dql_group = {
.name = "byte_queue_limits",
.attrs = dql_attrs,
};
#endif /* CONFIG_BQL */

#ifdef CONFIG_XPS
static inline unsigned int get_netdev_queue_index(struct netdev_queue *queue)
{
Expand Down Expand Up @@ -1096,17 +1207,17 @@ static struct attribute *netdev_queue_default_attrs[] = {
NULL
};

#ifdef CONFIG_XPS
static void netdev_queue_release(struct kobject *kobj)
{
struct netdev_queue *queue = to_netdev_queue(kobj);

#ifdef CONFIG_XPS
xps_queue_release(queue);
#endif

memset(kobj, 0, sizeof(*kobj));
dev_put(queue->dev);
}
#endif /* CONFIG_XPS */

static struct kobj_type netdev_queue_ktype = {
.sysfs_ops = &netdev_queue_sysfs_ops,
Expand All @@ -1125,14 +1236,21 @@ static int netdev_queue_add_kobject(struct net_device *net, int index)
kobj->kset = net->queues_kset;
error = kobject_init_and_add(kobj, &netdev_queue_ktype, NULL,
"tx-%u", index);
if (error) {
kobject_put(kobj);
return error;
}
if (error)
goto exit;

#ifdef CONFIG_BQL
error = sysfs_create_group(kobj, &dql_group);
if (error)
goto exit;
#endif

kobject_uevent(kobj, KOBJ_ADD);
dev_hold(queue->dev);

return 0;
exit:
kobject_put(kobj);
return error;
}
#endif /* CONFIG_SYSFS */
Expand All @@ -1152,8 +1270,14 @@ netdev_queue_update_kobjects(struct net_device *net, int old_num, int new_num)
}
}

while (--i >= new_num)
kobject_put(&net->_tx[i].kobj);
while (--i >= new_num) {
struct netdev_queue *queue = net->_tx + i;

#ifdef CONFIG_BQL
sysfs_remove_group(&queue->kobj, &dql_group);
#endif
kobject_put(&queue->kobj);
}

return error;
#else
Expand Down

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