mirror of
https://github.com/xdp-project/bpf-examples.git
synced 2024-05-06 15:54:53 +00:00
32 lines
829 B
Plaintext
32 lines
829 B
Plaintext
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#!/usr/local/bin/bpftrace
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#include <linux/skbuff.h>
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/* Measure time difference between EDT-time and real "NIC" TX-time.
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*
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* Assuming packets are EDT timestamped by the BPF-program, we can
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* detect/measure how accuratly packets are actually transmitted
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* towards the NIC driver, by comparing EDT-time against "now"
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* timestamp in the function transmitting to the NIC driver.
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*/
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// tracepoint:net:net_dev_start_xmit
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tracepoint:net:net_dev_xmit
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{
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$skb = (struct sk_buff *)args->skbaddr;
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//$tstamp = (uint64)$skb->tstamp;
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$tstamp = $skb->skb_mstamp_ns;
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$now = nsecs;
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// if ($skb->mark > 0) {
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if ($tstamp > 0) {
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if ($now >= $tstamp) {
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$diff_late = $now - $tstamp;
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} else {
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$diff_ahead = $tstamp - $now;
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}
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@tstamp_diff_late = hist($diff_late / 1000);
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@tstamp_diff_ahead = hist($diff_ahead / 1000);
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}
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}
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