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289 lines
15 KiB
Markdown
289 lines
15 KiB
Markdown
Example scripts for User-space, Statically Defined Tracing (USDT)
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=================================================================
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This directory contains scripts showcasing User-space, Statically Defined
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Tracing (USDT) support for Dash Core on Linux using. For more information on
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USDT support in Dash Core see the [USDT documentation].
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[USDT documentation]: ../../doc/tracing.md
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Examples for the two main eBPF front-ends, [bpftrace] and
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[BPF Compiler Collection (BCC)], with support for USDT, are listed. BCC is used
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for complex tools and daemons and `bpftrace` is preferred for one-liners and
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shorter scripts.
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[bpftrace]: https://github.com/iovisor/bpftrace
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[BPF Compiler Collection (BCC)]: https://github.com/iovisor/bcc
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To develop and run bpftrace and BCC scripts you need to install the
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corresponding packages. See [installing bpftrace] and [installing BCC] for more
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information. For development there exist a [bpftrace Reference Guide], a
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[BCC Reference Guide], and a [bcc Python Developer Tutorial].
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[installing bpftrace]: https://github.com/iovisor/bpftrace/blob/master/INSTALL.md
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[installing BCC]: https://github.com/iovisor/bcc/blob/master/INSTALL.md
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[bpftrace Reference Guide]: https://github.com/iovisor/bpftrace/blob/master/docs/reference_guide.md
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[BCC Reference Guide]: https://github.com/iovisor/bcc/blob/master/docs/reference_guide.md
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[bcc Python Developer Tutorial]: https://github.com/iovisor/bcc/blob/master/docs/tutorial_bcc_python_developer.md
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## Examples
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The bpftrace examples contain a relative path to the `dashd` binary. By
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default, the scripts should be run from the repository-root and assume a
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self-compiled `dashd` binary. The paths in the examples can be changed, for
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example, to point to release builds if needed. See the
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[Dash Core USDT documentation] on how to list available tracepoints in your
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`dashd` binary.
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[Dash Core USDT documentation]: ../../doc/tracing.md#listing-available-tracepoints
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**WARNING: eBPF programs require root privileges to be loaded into a Linux
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kernel VM. This means the bpftrace and BCC examples must be executed with root
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privileges. Make sure to carefully review any scripts that you run with root
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privileges first!**
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### log_p2p_traffic.bt
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A bpftrace script logging information about inbound and outbound P2P network
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messages. Based on the `net:inbound_message` and `net:outbound_message`
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tracepoints.
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By default, `bpftrace` limits strings to 64 bytes due to the limited stack size
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in the eBPF VM. For example, Tor v3 addresses exceed the string size limit which
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results in the port being cut off during logging. The string size limit can be
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increased with the `BPFTRACE_STRLEN` environment variable (`BPFTRACE_STRLEN=70`
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works fine).
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```
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$ bpftrace contrib/tracing/log_p2p_traffic.bt
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```
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Output
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```
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outbound 'ping' msg to peer 11 (outbound-full-relay, [2a02:b10c:f747:1:ef:fake:ipv6:addr]:8333) with 8 bytes
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inbound 'pong' msg from peer 11 (outbound-full-relay, [2a02:b10c:f747:1:ef:fake:ipv6:addr]:8333) with 8 bytes
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inbound 'inv' msg from peer 16 (outbound-full-relay, XX.XX.XXX.121:8333) with 37 bytes
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outbound 'getdata' msg to peer 16 (outbound-full-relay, XX.XX.XXX.121:8333) with 37 bytes
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inbound 'tx' msg from peer 16 (outbound-full-relay, XX.XX.XXX.121:8333) with 222 bytes
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outbound 'inv' msg to peer 9 (outbound-full-relay, faketorv3addressa2ufa6odvoi3s77j4uegey0xb10csyfyve2t33curbyd.onion:8333) with 37 bytes
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outbound 'inv' msg to peer 7 (outbound-full-relay, XX.XX.XXX.242:8333) with 37 bytes
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…
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```
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### p2p_monitor.py
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A BCC Python script using curses for an interactive P2P message monitor. Based
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on the `net:inbound_message` and `net:outbound_message` tracepoints.
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Inbound and outbound traffic is listed for each peer together with information
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about the connection. Peers can be selected individually to view recent P2P
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messages.
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```
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$ python3 contrib/tracing/p2p_monitor.py ./src/dashd
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```
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Lists selectable peers and traffic and connection information.
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```
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P2P Message Monitor
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Navigate with UP/DOWN or J/K and select a peer with ENTER or SPACE to see individual P2P messages
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PEER OUTBOUND INBOUND TYPE ADDR
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0 46 398 byte 61 1407590 byte block-relay-only XX.XX.XXX.196:8333
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11 1156 253570 byte 3431 2394924 byte outbound-full-relay XXX.X.XX.179:8333
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13 3425 1809620 byte 1236 305458 byte inbound XXX.X.X.X:60380
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16 1046 241633 byte 1589 1199220 byte outbound-full-relay 4faketorv2pbfu7x.onion:8333
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19 577 181679 byte 390 148951 byte outbound-full-relay kfake4vctorjv2o2.onion:8333
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20 11 1248 byte 13 1283 byte block-relay-only [2600:fake:64d9:b10c:4436:aaaa:fe:bb]:8333
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21 11 1248 byte 13 1299 byte block-relay-only XX.XXX.X.155:8333
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22 5 103 byte 1 102 byte feeler XX.XX.XXX.173:8333
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23 11 1248 byte 12 1255 byte block-relay-only XX.XXX.XXX.220:8333
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24 3 103 byte 1 102 byte feeler XXX.XXX.XXX.64:8333
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…
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```
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Showing recent P2P messages between our node and a selected peer.
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```
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----------------------------------------------------------------------
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| PEER 16 (4faketorv2pbfu7x.onion:8333) |
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| OUR NODE outbound-full-relay PEER |
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| <--- sendcmpct (9 bytes) |
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| inv (37 byte) ---> |
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| <--- ping (8 bytes) |
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| pong (8 byte) ---> |
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| inv (37 byte) ---> |
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| <--- addr (31 bytes) |
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| inv (37 byte) ---> |
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| <--- getheaders (1029 bytes) |
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| headers (1 byte) ---> |
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| <--- feefilter (8 bytes) |
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| <--- pong (8 bytes) |
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| <--- headers (82 bytes) |
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| <--- addr (30003 bytes) |
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| inv (1261 byte) ---> |
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| … |
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```
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### log_raw_p2p_msgs.py
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A BCC Python script showcasing eBPF and USDT limitations when passing data
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larger than about 32kb. Based on the `net:inbound_message` and
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`net:outbound_message` tracepoints.
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Dash P2P messages can be larger than 32kb (e.g. `tx`, `block`, ...). The
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eBPF VM's stack is limited to 512 bytes, and we can't allocate more than about
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32kb for a P2P message in the eBPF VM. The **message data is cut off** when the
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message is larger than MAX_MSG_DATA_LENGTH (see script). This can be detected
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in user-space by comparing the data length to the message length variable. The
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message is cut off when the data length is smaller than the message length.
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A warning is included with the printed message data.
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Data is submitted to user-space (i.e. to this script) via a ring buffer. The
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throughput of the ring buffer is limited. Each p2p_message is about 32kb in
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size. In- or outbound messages submitted to the ring buffer in rapid
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succession fill the ring buffer faster than it can be read. Some messages are
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lost. BCC prints: `Possibly lost 2 samples` on lost messages.
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```
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$ python3 contrib/tracing/log_raw_p2p_msgs.py ./src/dashd
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```
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```
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Logging raw P2P messages.
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Messages larger that about 32kb will be cut off!
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Some messages might be lost!
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outbound msg 'inv' from peer 4 (outbound-full-relay, XX.XXX.XX.4:8333) with 253 bytes: 0705000000be2245c8f844c9f763748e1a7…
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…
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Warning: incomplete message (only 32568 out of 53552 bytes)! inbound msg 'tx' from peer 32 (outbound-full-relay, XX.XXX.XXX.43:8333) with 53552 bytes: 020000000001fd3c01939c85ad6756ed9fc…
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…
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Possibly lost 2 samples
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```
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### connectblock_benchmark.bt
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A `bpftrace` script to benchmark the `ConnectBlock()` function during, for
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example, a blockchain re-index. Based on the `validation:block_connected` USDT
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tracepoint.
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The script takes three positional arguments. The first two arguments, the start,
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and end height indicate between which blocks the benchmark should be run. The
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third acts as a duration threshold in milliseconds. When the `ConnectBlock()`
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function takes longer than the threshold, information about the block, is
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printed. For more details, see the header comment in the script.
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The following command can be used to benchmark, for example, `ConnectBlock()`
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between height 20000 and 38000 on SigNet while logging all blocks that take
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longer than 25ms to connect.
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```
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$ bpftrace contrib/tracing/connectblock_benchmark.bt 20000 38000 25
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```
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In a different terminal, starting Dash Core in SigNet mode and with
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re-indexing enabled.
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```
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$ ./src/dashd -signet -reindex
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```
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This produces the following output.
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```
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Attaching 5 probes...
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ConnectBlock Benchmark between height 20000 and 38000 inclusive
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Logging blocks taking longer than 25 ms to connect.
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Starting Connect Block Benchmark between height 20000 and 38000.
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BENCH 39 blk/s 59 tx/s 59 inputs/s 20 sigops/s (height 20038)
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Block 20492 (000000f555653bb05e2f3c6e79925e01a20dd57033f4dc7c354b46e34735d32b) 20 tx 2319 ins 2318 sigops took 38 ms
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BENCH 1840 blk/s 2117 tx/s 4478 inputs/s 2471 sigops/s (height 21879)
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BENCH 1816 blk/s 4972 tx/s 4982 inputs/s 125 sigops/s (height 23695)
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BENCH 2095 blk/s 2890 tx/s 2910 inputs/s 152 sigops/s (height 25790)
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BENCH 1684 blk/s 3979 tx/s 4053 inputs/s 288 sigops/s (height 27474)
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BENCH 1155 blk/s 3216 tx/s 3252 inputs/s 115 sigops/s (height 28629)
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BENCH 1797 blk/s 2488 tx/s 2503 inputs/s 111 sigops/s (height 30426)
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BENCH 1849 blk/s 6318 tx/s 6569 inputs/s 12189 sigops/s (height 32275)
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BENCH 946 blk/s 20209 tx/s 20775 inputs/s 83809 sigops/s (height 33221)
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Block 33406 (0000002adfe4a15cfcd53bd890a89bbae836e5bb7f38bac566f61ad4548c87f6) 25 tx 2045 ins 2090 sigops took 29 ms
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Block 33687 (00000073231307a9828e5607ceb8156b402efe56747271a4442e75eb5b77cd36) 52 tx 1797 ins 1826 sigops took 26 ms
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BENCH 582 blk/s 21581 tx/s 27673 inputs/s 60345 sigops/s (height 33803)
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BENCH 1035 blk/s 19735 tx/s 19776 inputs/s 51355 sigops/s (height 34838)
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Block 35625 (0000006b00b347390c4768ea9df2655e9ff4b120f29d78594a2a702f8a02c997) 20 tx 3374 ins 3371 sigops took 49 ms
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BENCH 887 blk/s 17857 tx/s 22191 inputs/s 24404 sigops/s (height 35725)
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Block 35937 (000000d816d13d6e39b471cd4368db60463a764ba1f29168606b04a22b81ea57) 75 tx 3943 ins 3940 sigops took 61 ms
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BENCH 823 blk/s 16298 tx/s 21031 inputs/s 18440 sigops/s (height 36548)
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Block 36583 (000000c3e260556dbf42968aae3f904dba8b8c1ff96a6f6e3aa5365d2e3ad317) 24 tx 2198 ins 2194 sigops took 34 ms
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Block 36700 (000000b3b173de9e65a3cfa738d976af6347aaf83fa17ab3f2a4d2ede3ddfac4) 73 tx 1615 ins 1611 sigops took 31 ms
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Block 36832 (0000007859578c02c1ac37dabd1b9ec19b98f350b56935f5dd3a41e9f79f836e) 34 tx 1440 ins 1436 sigops took 26 ms
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BENCH 613 blk/s 16718 tx/s 25074 inputs/s 23022 sigops/s (height 37161)
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Block 37870 (000000f5c1086291ba2d943fb0c3bc82e71c5ee341ee117681d1456fbf6c6c38) 25 tx 1517 ins 1514 sigops took 29 ms
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BENCH 811 blk/s 16031 tx/s 20921 inputs/s 18696 sigops/s (height 37972)
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Took 14055 ms to connect the blocks between height 20000 and 38000.
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Histogram of block connection times in milliseconds (ms).
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@durations:
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[0] 16838 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
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[1] 882 |@@ |
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[2, 4) 236 | |
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[4, 8) 23 | |
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[8, 16) 9 | |
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[16, 32) 9 | |
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[32, 64) 4 | |
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```
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### log_utxocache_flush.py
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A BCC Python script to log the UTXO cache flushes. Based on the
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`utxocache:flush` tracepoint.
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```bash
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$ python3 contrib/tracing/log_utxocache_flush.py ./src/dashd
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```
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```
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Logging utxocache flushes. Ctrl-C to end...
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Duration (µs) Mode Coins Count Memory Usage Prune
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730451 IF_NEEDED 22990 3323.54 kB True
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637657 ALWAYS 122320 17124.80 kB False
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81349 ALWAYS 0 1383.49 kB False
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```
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### log_utxos.bt
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A `bpftrace` script to log information about the coins that are added, spent, or
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uncached from the UTXO set. Based on the `utxocache:add`, `utxocache:spend` and
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`utxocache:uncache` tracepoints.
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```bash
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$ bpftrace contrib/tracing/log_utxos.bt
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```
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This should produce an output similar to the following. If you see bpftrace
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warnings like `Lost 24 events`, the eBPF perf ring-buffer is filled faster
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than it is being read. You can increase the ring-buffer size by setting the
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ENV variable `BPFTRACE_PERF_RB_PAGES` (default 64) at a cost of higher
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memory usage. See the [bpftrace reference guide] for more information.
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[bpftrace reference guide]: https://github.com/iovisor/bpftrace/blob/master/docs/reference_guide.md#98-bpftrace_perf_rb_pages
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```bash
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Attaching 4 probes...
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OP Outpoint Value Height Coinbase
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Added 6ba9ad857e1ef2eb2a2c94f06813c414c7ab273e3d6bd7ad64e000315a887e7c:1 10000 2094512 No
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Spent fa7dc4db56637a151f6649d8f26732956d1c5424c82aae400a83d02b2cc2c87b:0 182264897 2094512 No
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Added eeb2f099b1af6a2a12e6ddd2eeb16fc5968582241d7f08ba202d28b60ac264c7:0 10000 2094512 No
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Added eeb2f099b1af6a2a12e6ddd2eeb16fc5968582241d7f08ba202d28b60ac264c7:1 182254756 2094512 No
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Added a0c7f4ec9cccef2d89672a624a4e6c8237a17572efdd4679eea9e9ee70d2db04:0 10072679 2094513 Yes
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Spent 25e0df5cc1aeb1b78e6056bf403e5e8b7e41f138060ca0a50a50134df0549a5e:2 540 2094508 No
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Spent 42f383c04e09c26a2378272ec33aa0c1bf4883ca5ab739e8b7e06be5a5787d61:1 3848399 2007724 No
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Added f85e3b4b89270863a389395cc9a4123e417ab19384cef96533c6649abd6b0561:0 3788399 2094513 No
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Added f85e3b4b89270863a389395cc9a4123e417ab19384cef96533c6649abd6b0561:2 540 2094513 No
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Spent a05880b8c77971ed0b9f73062c7c4cdb0ff3856ab14cbf8bc481ed571cd34b83:1 5591281046 2094511 No
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Added eb689865f7d957938978d6207918748f74e6aa074f47874724327089445b0960:0 5589696005 2094513 No
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Added eb689865f7d957938978d6207918748f74e6aa074f47874724327089445b0960:1 1565556 2094513 No
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```
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