| Message ID | 1472601634-531498-3-git-send-email-tom@herbertland.com |
|---|---|
| State | RFC, archived |
| Delegated to: | David Miller |
| Headers | show |
On Tue, 30 Aug 2016 17:00:32 -0700 Tom Herbert <tom@herbertland.com> wrote: > Add two fields to netdev_queue as head_cnt and tail_cnt. head_cnt is > incremented for every sent packet in netdev_tx_sent_queue and tail_cnt > is incremented by the number of packets in netdev_tx_completed_queue. > So then the number of inflight packets for a queue is simply > queue->head_cnt - queue->tail_cnt. > > Add inflight_pkts to be reported in sys-fs. I like the idea of BQL tracking inflight packets, because we could use this to determine _when_ qdisc bulking could be beneficial (activating xmit_more). Idea from NetDev1.1 slides[1] page 17, and experiment with BQL byte_queue_limits/limit_max on page 18 (which would really need a pkt count not a byte count) [1] http://people.netfilter.org/hawk/presentations/NetDev1.1_2016/net_performance_BoF.pdf [2] http://people.netfilter.org/hawk/presentations/NetDev1.1_2016/links.html
On Tue, 2016-08-30 at 17:00 -0700, Tom Herbert wrote: > Add two fields to netdev_queue as head_cnt and tail_cnt. head_cnt is > incremented for every sent packet in netdev_tx_sent_queue and tail_cnt > is incremented by the number of packets in netdev_tx_completed_queue. > So then the number of inflight packets for a queue is simply > queue->head_cnt - queue->tail_cnt. > > Add inflight_pkts to be reported in sys-fs. > > Signed-off-by: Tom Herbert <tom@herbertland.com> > --- > include/linux/netdevice.h | 4 ++++ > net/core/net-sysfs.c | 11 +++++++++++ > 2 files changed, 15 insertions(+) > > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h > index d122be9..487d1df 100644 > --- a/include/linux/netdevice.h > +++ b/include/linux/netdevice.h > @@ -592,6 +592,8 @@ struct netdev_queue { > > #ifdef CONFIG_BQL > struct dql dql; > + unsigned int head_cnt; > + unsigned int tail_cnt; > #endif > } ____cacheline_aligned_in_smp; > You probably should put these fields in the appropriate cache lines of "struct dql" : It will provide better cache behavior and fill holes.
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index d122be9..487d1df 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -592,6 +592,8 @@ struct netdev_queue { #ifdef CONFIG_BQL struct dql dql; + unsigned int head_cnt; + unsigned int tail_cnt; #endif } ____cacheline_aligned_in_smp; @@ -2958,6 +2960,7 @@ static inline void netdev_tx_sent_queue(struct netdev_queue *dev_queue, unsigned int bytes) { #ifdef CONFIG_BQL + dev_queue->head_cnt++; dql_queued(&dev_queue->dql, bytes); if (likely(dql_avail(&dev_queue->dql) >= 0)) @@ -2999,6 +3002,7 @@ static inline void netdev_tx_completed_queue(struct netdev_queue *dev_queue, if (unlikely(!bytes)) return; + dev_queue->tail_cnt += pkts; dql_completed(&dev_queue->dql, bytes); /* diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 6e4f347..5a33f6a 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1147,6 +1147,16 @@ static ssize_t bql_show_inflight(struct netdev_queue *queue, static struct netdev_queue_attribute bql_inflight_attribute = __ATTR(inflight, S_IRUGO, bql_show_inflight, NULL); +static ssize_t bql_show_inflight_pkts(struct netdev_queue *queue, + struct netdev_queue_attribute *attr, + char *buf) +{ + return sprintf(buf, "%u\n", queue->head_cnt - queue->tail_cnt); +} + +static struct netdev_queue_attribute bql_inflight_pkts_attribute = + __ATTR(inflight_pkts, S_IRUGO, bql_show_inflight_pkts, NULL); + #define BQL_ATTR(NAME, FIELD) \ static ssize_t bql_show_ ## NAME(struct netdev_queue *queue, \ struct netdev_queue_attribute *attr, \ @@ -1176,6 +1186,7 @@ static struct attribute *dql_attrs[] = { &bql_limit_min_attribute.attr, &bql_hold_time_attribute.attr, &bql_inflight_attribute.attr, + &bql_inflight_pkts_attribute.attr, NULL };
Add two fields to netdev_queue as head_cnt and tail_cnt. head_cnt is incremented for every sent packet in netdev_tx_sent_queue and tail_cnt is incremented by the number of packets in netdev_tx_completed_queue. So then the number of inflight packets for a queue is simply queue->head_cnt - queue->tail_cnt. Add inflight_pkts to be reported in sys-fs. Signed-off-by: Tom Herbert <tom@herbertland.com> --- include/linux/netdevice.h | 4 ++++ net/core/net-sysfs.c | 11 +++++++++++ 2 files changed, 15 insertions(+)