.

tools/pinglat.py

 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
-# pinglat - estimate upper bound for local and remote ICMP ECHO software processing latency
+# pinglat - estimate upper bound for local ICMP ECHO software processing latency
 from bcc import BPF
 from time import sleep
 
 # name of interface we are tracing on
 ifname="eth0"
 
-#icmp_echo_ip = BPF.ksymname("icmp_echo")
-#assert icmp_echo_ip != -1
-
 prog = r"""
 #include <linux/interrupt.h>
 #include <linux/icmp.h>
@@ -22,22 +19,17 @@ struct event {
                         //   we take conservative approach and start counting time from the first )
 
     u64 techo;          // t when it got to icmp_echo
-//    u64 techo_reply;    // t when icmp_echo finished (it calls icmp_reply inside)
+    //u64 techo_reply;  // t when icmp_echo finished (it calls icmp_reply inside)
+                        //   we do not need to store it as this is the last point of the event
 };
 
 BPF_ARRAY(event, struct event, 1);  // current in-flight event
 
-// BPF_ARRAY(tlastint, u64, 1);    // t of last interrupt on iface
-// BPF_ARRAY(tlastecho, u64, 1);   // t of last icmp_echo
-
 BPF_HISTOGRAM(dist_dt_int_echo);    // dt int - icmp_echo
 BPF_HISTOGRAM(dist_dt_echo_tx);     // dt icmp_echo - tx
 BPF_HISTOGRAM(dist_dt_int_tx);      // dt int - tx
 BPF_HISTOGRAM(dist_nint);
 
-// // for determining call stack in net_dev_xmit; 1024 - not 1 - because calls can be done concurrently
-// BPF_STACK_TRACE(traceback, 1024);
-
 // # out-of-sync events
 // 1 - missed interrupt
 // 2 - second icmp_echo without processing for first completed
@@ -60,11 +52,6 @@ prog += r"""
     int z=0; struct event zev = {};
 
     struct event *ev = event.lookup_or_init(&z, &zev);
-    //if (ev->tint != 0) {
-    //    // interrupt came but icmp_echo not yet handled
-    //    ev->nint++;
-    //    return 0;
-    //}
 
     ev->tint = ts;  // t of _last_ interrupt
     ev->nint++;     // verifying it is sane (e.g. =2 means TXintr RXintr icmp_echo icmp_reply TXintr RXintr ...
@@ -94,15 +81,6 @@ int kprobe__icmp_echo(struct pt_regs *ctx, struct sk_buff *skb) {
 
     ev->techo = ts;
 
-    // update t(int) - t(icmp_echo) along the way
-    //struct icmphdr h;
-    //bpf_probe_read(&h, sizeof(h), skb->head + skb->transport_header); // = icmp_hdr(skb)
-
-    //u64 tint = *tlastint.lookup_or_init(&z, &z64);
-
-    //u64 dt = ts - tint;
-    //dist_dt_int_echo.increment(bpf_log2l(dt / (u64)(1E3)));
-
     //bpf_trace_printk("ping id: %d  seq: %d  dint: %dns\n", h.un.echo.id, h.un.echo.sequence, ts - tint);
     return 0;
 }
@@ -144,60 +122,7 @@ int kretprobe__icmp_echo(struct pt_regs *ctx) {
 }
 """
 
-# # devname != ifname -> return
-# prog += "    char c;\n"
-# for i, c in enumerate(ifname):
-#     prog += "    bpf_probe_read(&c, 1, &devname[%d]);   if (c != '%s') return 0;\n" % (i, c)
-#
-#
-# prog += r"""
-#     // make sure tx is called from under icmp_echo - if not - ignore
-#     // 0      0      swapper/1    net_dev_xmit
-#     //         dev_hard_start_xmit+0x123 [kernel]
-#     //         dev_hard_start_xmit+0x123 [kernel]
-#     //         sch_direct_xmit+0xf1 [kernel]
-#     //         __dev_queue_xmit+0x45a [kernel]
-#     //         ip_finish_output2+0x2a8 [kernel]
-#     //         ip_output+0x72 [kernel]
-#     //         ip_output+0x72 [kernel]
-#     //         ip_send_skb+0x15 [kernel]
-#     //         icmp_reply.constprop.25+0x24f [kernel]
-#     //         icmp_echo.part.23+0x5e [kernel]
-#     //         skb_checksum+0x32 [kernel]
-#     //         csum_partial_ext+0x0 [kernel]
-#     //         csum_block_add_ext+0x0 [kernel]
-#     //         __skb_checksum_complete+0x1c [kernel]
-#     //         icmp_echo+0x27 [kernel]                 <--
-#     //         icmp_rcv+0x26f [kernel]
-#     int stkid = traceback.get_stackid(args, 14 | BPF_F_REUSE_STACKID);  // XXX recheck 14 skip, fragile
-#     if (stkid < 0) {
-#         return 0; // error
-#     }
-#
-#     struct bpf_stacktrace *tb;
-#     tb = traceback.lookup(&stkid);
-#     if (!(ICMP_ECHO_IP <= tb->ip[0] && tb->ip[0] < ICMP_ECHO_IP + 0x40)) {    // XXX fragile
-#         return 0;   // called not from under icmp_echo
-#     }
-#
-#     bpf_trace_printk("net tx from under icmp_echo\n");
-#     return 0;
-#
-#
-#     int z=0; u64 z64=0;
-#     u64 ts = bpf_ktime_get_ns();
-#
-#     u64 dtint  = ts - *tlastint.lookup_or_init(&z, &z64);
-#     u64 dtecho = ts - *tlastecho.lookup_or_init(&z, &z64);
-#
-#     dist_dt_echo_tx.increment(bpf_log2l(dtecho / (u64)(1E3)));
-#     dist_dt_int_tx .increment(bpf_log2l(dtint  / (u64)(1E3)));
-#
-#     return 0;
-# }
-# """
 prog = prog.replace("IFNAME", ifname)
-#prog = prog.replace("ICMP_ECHO_IP", "0x%x" % icmp_echo_ip)
 
 #print prog