bpftrace_queued_bytes.bt

#include <linux/skbuff.h>
#include <linux/netdevice.h>

// USER TODO: fill in device_name
// The script will start measuring when the device is reset (ip l s net0 down; ip l s net0 up)
// This is to avoid dealing w network traffic occuring before tracing started 
BEGIN {
 @device_name = "net0";
 @start = 0;
}

kprobe:netif_tx_stop_all_queues {
    if (@start == 1) {
        exit();
    }
    @start = 1;
}

// record the number of bytes being queued to a particular queue
tracepoint:net:net_dev_queue /str(args->name) == @device_name && @start/ {
    $queue = ((struct sk_buff *)args->skbaddr)->queue_mapping;
    @bytes_queued[$queue] += args->len;
}

// record the number of bytes that were dequeued from a particular queue and update the histogram
tracepoint:net:net_dev_start_xmit /@bytes_queued[args->queue_mapping] && str(args->name) == @device_name && @start/ {
    if (@bytes_queued[args->queue_mapping] <= args->len){
        @bytes_queued[args->queue_mapping] = 0;
    }
    else {
        @bytes_queued[args->queue_mapping] -= args->len;
    }
    @outstanding_bytes[args->queue_mapping] = hist(@bytes_queued[args->queue_mapping]);
}