From 8f37f5c2a562c38c83fc40234ade9c301fc4e685 Mon Sep 17 00:00:00 2001 From: 0xb10c <0xb10c@gmail.com> Date: Thu, 20 May 2021 17:53:24 +0200 Subject: [PATCH] tracing: Tracepoint for connected blocks Can, for example, be used to benchmark block connections. --- contrib/tracing/README.md | 76 +++++++++++ contrib/tracing/connectblock_benchmark.bt | 150 ++++++++++++++++++++++ doc/tracing.md | 22 ++++ src/validation.cpp | 11 ++ 4 files changed, 259 insertions(+) create mode 100755 contrib/tracing/connectblock_benchmark.bt diff --git a/contrib/tracing/README.md b/contrib/tracing/README.md index 2d81e375dc5..047354cda17 100644 --- a/contrib/tracing/README.md +++ b/contrib/tracing/README.md @@ -163,3 +163,79 @@ Warning: incomplete message (only 32568 out of 53552 bytes)! inbound msg 'tx' fr … Possibly lost 2 samples ``` + +### connectblock_benchmark.bt + +A `bpftrace` script to benchmark the `ConnectBlock()` function during, for +example, a blockchain re-index. Based on the `validation:block_connected` USDT +tracepoint. + +The script takes three positional arguments. The first two arguments, the start, +and end height indicate between which blocks the benchmark should be run. The +third acts as a duration threshold in milliseconds. When the `ConnectBlock()` +function takes longer than the threshold, information about the block, is +printed. For more details, see the header comment in the script. + +By default, `bpftrace` limits strings to 64 bytes due to the limited stack size +in the kernel VM. Block hashes as zero-terminated hex strings are 65 bytes which +exceed the string limit. The string size limit can be set to 65 bytes with the +environment variable `BPFTRACE_STRLEN`. + +The following command can be used to benchmark, for example, `ConnectBlock()` +between height 20000 and 38000 on SigNet while logging all blocks that take +longer than 25ms to connect. + +``` +$ BPFTRACE_STRLEN=65 bpftrace contrib/tracing/connectblock_benchmark.bt 20000 38000 25 +``` + +In a different terminal, starting Bitcoin Core in SigNet mode and with +re-indexing enabled. + +``` +$ ./src/bitcoind -signet -reindex +``` + +This produces the following output. +``` +Attaching 5 probes... +ConnectBlock Benchmark between height 20000 and 38000 inclusive +Logging blocks taking longer than 25 ms to connect. +Starting Connect Block Benchmark between height 20000 and 38000. +BENCH 39 blk/s 59 tx/s 59 inputs/s 20 sigops/s (height 20038) +Block 20492 (000000f555653bb05e2f3c6e79925e01a20dd57033f4dc7c354b46e34735d32b) 20 tx 2319 ins 2318 sigops took 38 ms +BENCH 1840 blk/s 2117 tx/s 4478 inputs/s 2471 sigops/s (height 21879) +BENCH 1816 blk/s 4972 tx/s 4982 inputs/s 125 sigops/s (height 23695) +BENCH 2095 blk/s 2890 tx/s 2910 inputs/s 152 sigops/s (height 25790) +BENCH 1684 blk/s 3979 tx/s 4053 inputs/s 288 sigops/s (height 27474) +BENCH 1155 blk/s 3216 tx/s 3252 inputs/s 115 sigops/s (height 28629) +BENCH 1797 blk/s 2488 tx/s 2503 inputs/s 111 sigops/s (height 30426) +BENCH 1849 blk/s 6318 tx/s 6569 inputs/s 12189 sigops/s (height 32275) +BENCH 946 blk/s 20209 tx/s 20775 inputs/s 83809 sigops/s (height 33221) +Block 33406 (0000002adfe4a15cfcd53bd890a89bbae836e5bb7f38bac566f61ad4548c87f6) 25 tx 2045 ins 2090 sigops took 29 ms +Block 33687 (00000073231307a9828e5607ceb8156b402efe56747271a4442e75eb5b77cd36) 52 tx 1797 ins 1826 sigops took 26 ms +BENCH 582 blk/s 21581 tx/s 27673 inputs/s 60345 sigops/s (height 33803) +BENCH 1035 blk/s 19735 tx/s 19776 inputs/s 51355 sigops/s (height 34838) +Block 35625 (0000006b00b347390c4768ea9df2655e9ff4b120f29d78594a2a702f8a02c997) 20 tx 3374 ins 3371 sigops took 49 ms +BENCH 887 blk/s 17857 tx/s 22191 inputs/s 24404 sigops/s (height 35725) +Block 35937 (000000d816d13d6e39b471cd4368db60463a764ba1f29168606b04a22b81ea57) 75 tx 3943 ins 3940 sigops took 61 ms +BENCH 823 blk/s 16298 tx/s 21031 inputs/s 18440 sigops/s (height 36548) +Block 36583 (000000c3e260556dbf42968aae3f904dba8b8c1ff96a6f6e3aa5365d2e3ad317) 24 tx 2198 ins 2194 sigops took 34 ms +Block 36700 (000000b3b173de9e65a3cfa738d976af6347aaf83fa17ab3f2a4d2ede3ddfac4) 73 tx 1615 ins 1611 sigops took 31 ms +Block 36832 (0000007859578c02c1ac37dabd1b9ec19b98f350b56935f5dd3a41e9f79f836e) 34 tx 1440 ins 1436 sigops took 26 ms +BENCH 613 blk/s 16718 tx/s 25074 inputs/s 23022 sigops/s (height 37161) +Block 37870 (000000f5c1086291ba2d943fb0c3bc82e71c5ee341ee117681d1456fbf6c6c38) 25 tx 1517 ins 1514 sigops took 29 ms +BENCH 811 blk/s 16031 tx/s 20921 inputs/s 18696 sigops/s (height 37972) + +Took 14055 ms to connect the blocks between height 20000 and 38000. + +Histogram of block connection times in milliseconds (ms). +@durations: +[0] 16838 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@| +[1] 882 |@@ | +[2, 4) 236 | | +[4, 8) 23 | | +[8, 16) 9 | | +[16, 32) 9 | | +[32, 64) 4 | | +``` diff --git a/contrib/tracing/connectblock_benchmark.bt b/contrib/tracing/connectblock_benchmark.bt new file mode 100755 index 00000000000..d268eff7f8b --- /dev/null +++ b/contrib/tracing/connectblock_benchmark.bt @@ -0,0 +1,150 @@ +#!/usr/bin/env bpftrace + +/* + + USAGE: + + BPFTRACE_STRLEN=65 bpftrace contrib/tracing/connectblock_benchmark.bt + + - The environment variable BPFTRACE_STRLEN needs to be set to 65 chars as + strings are limited to 64 chars by default. Hex strings with Bitcoin block + hashes are 64 hex chars + 1 null-termination char. + - sets the height at which the benchmark should start. Setting + the start height to 0 starts the benchmark immediately, even before the + first block is connected. + - sets the height after which the benchmark should end. Setting + the end height to 0 disables the benchmark. The script only logs blocks + over . + - Threshold + + This script requires a 'bitcoind' binary compiled with eBPF support and the + 'validation:block_connected' USDT. By default, it's assumed that 'bitcoind' is + located in './src/bitcoind'. This can be modified in the script below. + + EXAMPLES: + + BPFTRACE_STRLEN=65 bpftrace contrib/tracing/connectblock_benchmark.bt 300000 680000 1000 + + When run together 'bitcoind -reindex', this benchmarks the time it takes to + connect the blocks between height 300.000 and 680.000 (inclusive) and prints + details about all blocks that take longer than 1000ms to connect. Prints a + histogram with block connection times when the benchmark is finished. + + + BPFTRACE_STRLEN=65 bpftrace contrib/tracing/connectblock_benchmark.bt 0 0 500 + + When running together 'bitcoind', all newly connected blocks that + take longer than 500ms to connect are logged. A histogram with block + connection times is shown when the script is terminated. + +*/ + +BEGIN +{ + $start_height = $1; + $end_height = $2; + $logging_threshold_ms = $3; + + if ($end_height < $start_height) { + printf("Error: start height (%d) larger than end height (%d)!\n", $start_height, $end_height); + exit(); + } + + if ($end_height > 0) { + printf("ConnectBlock benchmark between height %d and %d inclusive\n", $start_height, $end_height); + } else { + printf("ConnectBlock logging starting at height %d\n", $start_height); + } + + if ($logging_threshold_ms > 0) { + printf("Logging blocks taking longer than %d ms to connect.\n", $3); + } + + if ($start_height == 0) { + @start = nsecs; + } +} + +/* + Attaches to the 'validation:block_connected' USDT and collects stats when the + connected block is between the start and end height (or the end height is + unset). +*/ +usdt:./src/bitcoind:validation:block_connected /arg1 >= $1 && (arg1 <= $2 || $2 == 0 )/ +{ + $height = arg1; + $transactions = arg2; + $inputs = arg3; + $sigops = arg4; + $duration = (uint64) arg5; + + @height = $height; + + @blocks = @blocks + 1; + @transactions = @transactions + $transactions; + @inputs = @inputs + $inputs; + @sigops = @sigops + $sigops; + + @durations = hist($duration / 1000); + + if ($height == $1 && $height != 0) { + @start = nsecs; + printf("Starting Connect Block Benchmark between height %d and %d.\n", $1, $2); + } + + if ($2 > 0 && $height >= $2) { + @end = nsecs; + $duration = @end - @start; + printf("\nTook %d ms to connect the blocks between height %d and %d.\n", $duration / 1000000, $1, $2); + exit(); + } +} + +/* + Attaches to the 'validation:block_connected' USDT and logs information about + blocks where the time it took to connect the block is above the + . +*/ +usdt:./src/bitcoind:validation:block_connected / (uint64) arg5 / 1000> $3 / +{ + $hash_str = str(arg0); + $height = (int32) arg1; + $transactions = (uint64) arg2; + $inputs = (int32) arg3; + $sigops = (int64) arg4; + $duration = (int64) arg5; + + printf("Block %d (%s) %4d tx %5d ins %5d sigops took %4d ms\n", $height, $hash_str, $transactions, $inputs, $sigops, (uint64) $duration / 1000); +} + + +/* + Prints stats about the blocks, transactions, inputs, and sigops processed in + the last second (if any). +*/ +interval:s:1 { + if (@blocks > 0) { + printf("BENCH %4d blk/s %6d tx/s %7d inputs/s %8d sigops/s (height %d)\n", @blocks, @transactions, @inputs, @sigops, @height); + + zero(@blocks); + zero(@transactions); + zero(@inputs); + zero(@sigops); + } +} + +END +{ + printf("\nHistogram of block connection times in milliseconds (ms).\n"); + print(@durations); + + clear(@durations); + clear(@blocks); + clear(@transactions); + clear(@inputs); + clear(@sigops); + clear(@height); + clear(@start); + clear(@end); +} + diff --git a/doc/tracing.md b/doc/tracing.md index 026946b0188..1242a0d2500 100644 --- a/doc/tracing.md +++ b/doc/tracing.md @@ -93,6 +93,28 @@ to user-space in full. Messages longer than a 32kb might be cut off. This can be detected in tracing scripts by comparing the message size to the length of the passed message. +### Context `validation` + +#### Tracepoint `validation:block_connected` + +Is called *after* a block is connected to the chain. Can, for example, be used +to benchmark block connections together with `-reindex`. + +Arguments passed: +1. Block Header Hash as `pointer to C-style String` (64 characters) +2. Block Height as `int32` +3. Transactions in the Block as `uint64` +4. Inputs spend in the Block as `int32` +5. SigOps in the Block (excluding coinbase SigOps) `uint64` +6. Time it took to connect the Block in microseconds (µs) as `uint64` +7. Block Header Hash as `pointer to unsigned chars` (i.e. 32 bytes in little-endian) + +Note: The 7th argument can't be accessed by bpftrace and is purposefully chosen +to be the block header hash as bytes. See [bpftrace argument limit] for more +details. + +[bpftrace argument limit]: #bpftrace-argument-limit + ## Adding tracepoints to Bitcoin Core To add a new tracepoint, `#include ` in the compilation unit where diff --git a/src/validation.cpp b/src/validation.cpp index 4e7bc635da8..20d641bf400 100644 --- a/src/validation.cpp +++ b/src/validation.cpp @@ -48,6 +48,7 @@ #include #include #include +#include #include #include #include @@ -1997,6 +1998,16 @@ bool CChainState::ConnectBlock(const CBlock& block, BlockValidationState& state, int64_t nTime6 = GetTimeMicros(); nTimeCallbacks += nTime6 - nTime5; LogPrint(BCLog::BENCH, " - Callbacks: %.2fms [%.2fs (%.2fms/blk)]\n", MILLI * (nTime6 - nTime5), nTimeCallbacks * MICRO, nTimeCallbacks * MILLI / nBlocksTotal); + TRACE7(validation, block_connected, + block.GetHash().ToString().c_str(), + pindex->nHeight, + block.vtx.size(), + nInputs, + nSigOpsCost, + GetTimeMicros() - nTimeStart, // in microseconds (µs) + block.GetHash().data() + ); + return true; }