From 53c9fa9e6253ea89ba1057b35e018ad1a25fb97e Mon Sep 17 00:00:00 2001 From: 0xb10c <0xb10c@gmail.com> Date: Mon, 18 Oct 2021 13:19:13 +0200 Subject: tracing: drop block_connected hash.toString() arg The tracepoint `validation:block_connected` was introduced in #22006. The first argument was the hash of the connected block as a pointer to a C-like String. The last argument passed the hash of the connected block as a pointer to 32 bytes. The hash was only passed as string to allow `bpftrace` scripts to print the hash. It was (incorrectly) assumed that `bpftrace` cannot hex-format and print the block hash given only the hash as bytes. The block hash can be printed in `bpftrace` by calling `printf("%02x")` for each byte of the hash in an `unroll () {...}`. By starting from the last byte of the hash, it can be printed in big-endian (the block-explorer format). ```C $p = $hash + 31; unroll(32) { $b = *(uint8*)$p; printf("%02x", $b); $p -= 1; } ``` See also: https://github.com/bitcoin/bitcoin/pull/22902#discussion_r705176691 This is a breaking change to the block_connected tracepoint API, however this tracepoint has not yet been included in a release. --- contrib/tracing/README.md | 7 +------ contrib/tracing/connectblock_benchmark.bt | 22 ++++++++++++++-------- 2 files changed, 15 insertions(+), 14 deletions(-) (limited to 'contrib') diff --git a/contrib/tracing/README.md b/contrib/tracing/README.md index 047354cda1..1f93474fa0 100644 --- a/contrib/tracing/README.md +++ b/contrib/tracing/README.md @@ -176,17 +176,12 @@ third acts as a duration threshold in milliseconds. When the `ConnectBlock()` function takes longer than the threshold, information about the block, is printed. For more details, see the header comment in the script. -By default, `bpftrace` limits strings to 64 bytes due to the limited stack size -in the kernel VM. Block hashes as zero-terminated hex strings are 65 bytes which -exceed the string limit. The string size limit can be set to 65 bytes with the -environment variable `BPFTRACE_STRLEN`. - The following command can be used to benchmark, for example, `ConnectBlock()` between height 20000 and 38000 on SigNet while logging all blocks that take longer than 25ms to connect. ``` -$ BPFTRACE_STRLEN=65 bpftrace contrib/tracing/connectblock_benchmark.bt 20000 38000 25 +$ bpftrace contrib/tracing/connectblock_benchmark.bt 20000 38000 25 ``` In a different terminal, starting Bitcoin Core in SigNet mode and with diff --git a/contrib/tracing/connectblock_benchmark.bt b/contrib/tracing/connectblock_benchmark.bt index d268eff7f8..6e7a98ef07 100755 --- a/contrib/tracing/connectblock_benchmark.bt +++ b/contrib/tracing/connectblock_benchmark.bt @@ -4,11 +4,8 @@ USAGE: - BPFTRACE_STRLEN=65 bpftrace contrib/tracing/connectblock_benchmark.bt + 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. @@ -23,7 +20,7 @@ EXAMPLES: - BPFTRACE_STRLEN=65 bpftrace contrib/tracing/connectblock_benchmark.bt 300000 680000 1000 + 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 @@ -31,7 +28,7 @@ histogram with block connection times when the benchmark is finished. - BPFTRACE_STRLEN=65 bpftrace contrib/tracing/connectblock_benchmark.bt 0 0 500 + 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 @@ -107,14 +104,23 @@ usdt:./src/bitcoind:validation:block_connected /arg1 >= $1 && (arg1 <= $2 || $2 */ usdt:./src/bitcoind:validation:block_connected / (uint64) arg5 / 1000> $3 / { - $hash_str = str(arg0); + $hash = 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); + + printf("Block %d (", $height); + /* Prints each byte of the block hash as hex in big-endian (the block-explorer format) */ + $p = $hash + 31; + unroll(32) { + $b = *(uint8*)$p; + printf("%02x", $b); + $p -= 1; + } + printf(") %4d tx %5d ins %5d sigops took %4d ms\n", $transactions, $inputs, $sigops, (uint64) $duration / 1000); } -- cgit v1.2.3