diff options
| -rw-r--r-- | contrib/tracing/README.md | 8 | ||||
| -rwxr-xr-x | contrib/tracing/log_utxocache_flush.py | 11 | ||||
| -rwxr-xr-x | contrib/tracing/log_utxos.bt | 2 | ||||
| -rw-r--r-- | doc/tracing.md | 32 |
4 files changed, 36 insertions, 17 deletions
diff --git a/contrib/tracing/README.md b/contrib/tracing/README.md index 05d2c8f9cf..a409a23ef8 100644 --- a/contrib/tracing/README.md +++ b/contrib/tracing/README.md @@ -262,7 +262,13 @@ uncached from the UTXO set. Based on the `utxocache:add`, `utxocache:spend` and $ bpftrace contrib/tracing/log_utxos.bt ``` -It should produce an output similar to the following. +This should produce an output similar to the following. If you see bpftrace +warnings like `Lost 24 events`, the eBPF perf ring-buffer is filled faster +than it is being read. You can increase the ring-buffer size by setting the +ENV variable `BPFTRACE_PERF_RB_PAGES` (default 64) at a cost of higher +memory usage. See the [bpftrace reference guide] for more information. + +[bpftrace reference guide]: https://github.com/iovisor/bpftrace/blob/master/docs/reference_guide.md#98-bpftrace_perf_rb_pages ```bash Attaching 4 probes... diff --git a/contrib/tracing/log_utxocache_flush.py b/contrib/tracing/log_utxocache_flush.py index 3326346b50..24ede0fe14 100755 --- a/contrib/tracing/log_utxocache_flush.py +++ b/contrib/tracing/log_utxocache_flush.py @@ -13,13 +13,14 @@ from bcc import BPF, USDT # a sandboxed Linux kernel VM. program = """ # include <uapi/linux/ptrace.h> + struct data_t { u64 duration; u32 mode; u64 coins_count; u64 coins_mem_usage; - bool is_flush_prune; + bool is_flush_for_prune; }; // BPF perf buffer to push the data to user space. @@ -31,7 +32,7 @@ int trace_flush(struct pt_regs *ctx) { bpf_usdt_readarg(2, ctx, &data.mode); bpf_usdt_readarg(3, ctx, &data.coins_count); bpf_usdt_readarg(4, ctx, &data.coins_mem_usage); - bpf_usdt_readarg(5, ctx, &data.is_flush_prune); + bpf_usdt_readarg(5, ctx, &data.is_flush_for_prune); flush.perf_submit(ctx, &data, sizeof(data)); return 0; } @@ -52,7 +53,7 @@ class Data(ctypes.Structure): ("mode", ctypes.c_uint32), ("coins_count", ctypes.c_uint64), ("coins_mem_usage", ctypes.c_uint64), - ("is_flush_prune", ctypes.c_bool), + ("is_flush_for_prune", ctypes.c_bool) ] @@ -62,7 +63,7 @@ def print_event(event): FLUSH_MODES[event.mode], event.coins_count, "%.2f kB" % (event.coins_mem_usage/1000), - event.is_flush_prune, + event.is_flush_for_prune )) @@ -85,7 +86,7 @@ def main(bitcoind_path): print("Logging utxocache flushes. Ctrl-C to end...") print("%-15s %-10s %-15s %-15s %-8s" % ("Duration (µs)", "Mode", "Coins Count", "Memory Usage", - "Prune")) + "Flush for Prune")) while True: try: diff --git a/contrib/tracing/log_utxos.bt b/contrib/tracing/log_utxos.bt index 0d47f3d62b..54d5010f82 100755 --- a/contrib/tracing/log_utxos.bt +++ b/contrib/tracing/log_utxos.bt @@ -7,7 +7,7 @@ bpftrace contrib/tracing/log_utxos.bt This script requires a 'bitcoind' binary compiled with eBPF support and the - 'utxochache' tracepoints. By default, it's assumed that 'bitcoind' is + 'utxocache' tracepoints. By default, it's assumed that 'bitcoind' is located in './src/bitcoind'. This can be modified in the script below. NOTE: requires bpftrace v0.12.0 or above. diff --git a/doc/tracing.md b/doc/tracing.md index 68de376043..6ec6a6c218 100644 --- a/doc/tracing.md +++ b/doc/tracing.md @@ -110,22 +110,31 @@ Arguments passed: ### Context `utxocache` +The following tracepoints cover the in-memory UTXO cache. UTXOs are, for example, +added to and removed (spent) from the cache when we connect a new block. +**Note**: Bitcoin Core uses temporary clones of the _main_ UTXO cache +(`chainstate.CoinsTip()`). For example, the RPCs `generateblock` and +`getblocktemplate` call `TestBlockValidity()`, which applies the UTXO set +changes to a temporary cache. Similarly, mempool consistency checks, which are +frequent on regtest, also apply the the UTXO set changes to a temporary cache. +Changes to the _main_ UTXO cache and to temporary caches trigger the tracepoints. +We can't tell if a temporary cache or the _main_ cache was changed. + #### Tracepoint `utxocache:flush` -Is called *after* the caches are flushed depending on the mode -`CChainState::FlushStateToDisk` is called with. +Is called *after* the in-memory UTXO cache is flushed. Arguments passed: -1. Duration in microseconds as `int64` +1. Time it took to flush the cache microseconds as `int64` 2. Flush state mode as `uint32`. It's an enumerator class with values `0` (`NONE`), `1` (`IF_NEEDED`), `2` (`PERIODIC`), `3` (`ALWAYS`) -3. Number of coins flushed as `uint64` -4. Memory usage in bytes as `uint64` -5. If the flush was pruned as `bool` +3. Cache size (number of coins) before the flush as `uint64` +4. Cache memory usage in bytes as `uint64` +5. If pruning caused the flush as `bool` #### Tracepoint `utxocache:add` -It is called when a new coin is added to the UTXO cache. +Is called when a coin is added to a UTXO cache. This can be a temporary UTXO cache too. Arguments passed: 1. Transaction ID (hash) as `pointer to unsigned chars` (i.e. 32 bytes in little-endian) @@ -136,7 +145,7 @@ Arguments passed: #### Tracepoint `utxocache:spent` -It is called when a coin is spent from the UTXO cache. +Is called when a coin is spent from a UTXO cache. This can be a temporary UTXO cache too. Arguments passed: 1. Transaction ID (hash) as `pointer to unsigned chars` (i.e. 32 bytes in little-endian) @@ -147,14 +156,17 @@ Arguments passed: #### Tracepoint `utxocache:uncache` -It is called when the UTXO with the given outpoint is removed from the cache. +Is called when a coin is purposefully unloaded from a UTXO cache. This +happens, for example, when we load an UTXO into a cache when trying to accept +a transaction that turns out to be invalid. The loaded UTXO is uncached to avoid +filling our UTXO cache up with irrelevant UTXOs. Arguments passed: 1. Transaction ID (hash) as `pointer to unsigned chars` (i.e. 32 bytes in little-endian) 2. Output index as `uint32` 3. Block height the coin was uncached, as `uint32` 4. Value of the coin as `int64` -. If the coin is a coinbase as `bool` +5. If the coin is a coinbase as `bool` ## Adding tracepoints to Bitcoin Core |