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fix rocksdb block cache size #122

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Merged
andresilva merged 3 commits into from
May 7, 2019
Merged

fix rocksdb block cache size #122

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8fd282d
rocksdb: use KB and MB as constants
ordian Apr 11, 2019
85d6003
fix(rocksdb): cap block lru cache in 8 MB, not 8 bytes
ordian Apr 11, 2019
4ddbe03
rocksdb: remove the minimum on block cache size, add a comment
ordian Apr 11, 2019
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16 changes: 9 additions & 7 deletions kvdb-rocksdb/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,8 @@ fn other_io_err<E>(e: E) -> io::Error where E: Into<Box<error::Error + Send + Sy
io::Error::new(io::ErrorKind::Other, e)
}

const KB: usize = 1024;
const MB: usize = 1024 * KB;
const DB_DEFAULT_MEMORY_BUDGET_MB: usize = 128;

enum KeyState {
Expand Down Expand Up @@ -142,18 +144,18 @@ impl CompactionProfile {
/// Default profile suitable for SSD storage
pub fn ssd() -> CompactionProfile {
CompactionProfile {
initial_file_size: 64 * 1024 * 1024,
block_size: 16 * 1024,
initial_file_size: 64 * MB as u64,
block_size: 16 * KB,
write_rate_limit: None,
}
}

/// Slow HDD compaction profile
pub fn hdd() -> CompactionProfile {
CompactionProfile {
initial_file_size: 256 * 1024 * 1024,
block_size: 64 * 1024,
write_rate_limit: Some(16 * 1024 * 1024),
initial_file_size: 256 * MB as u64,
block_size: 64 * KB,
write_rate_limit: Some(16 * MB as u64),
}
}
}
Expand Down Expand Up @@ -181,7 +183,7 @@ impl DatabaseConfig {
}

pub fn memory_budget(&self) -> usize {
self.memory_budget.unwrap_or(DB_DEFAULT_MEMORY_BUDGET_MB) * 1024 * 1024
self.memory_budget.unwrap_or(DB_DEFAULT_MEMORY_BUDGET_MB) * MB
}

pub fn memory_budget_per_col(&self) -> usize {
Expand Down Expand Up @@ -303,7 +305,7 @@ impl Database {

{
block_opts.set_block_size(config.compaction.block_size);
let cache_size = cmp::max(8, config.memory_budget() / 3);
let cache_size = cmp::max(8 * MB, config.memory_budget() / 3);

@ordian ordian Apr 11, 2019 •
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I wonder where does this / 3 come from, should it be / columns?
EDIT: probably not, but still curious.

@ordian ordian Apr 11, 2019

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cc @andresilva (openethereum/parity-ethereum#7348)

@andresilva andresilva Apr 11, 2019

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Nice catch. I think I got that one third from here: https://github.com/facebook/rocksdb/wiki/Setup-Options-and-Basic-Tuning#block-cache-size

@dvdplm dvdplm Apr 11, 2019

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One option is to simply take config.memory_budget() / 3 and assume that if someone changes that to something below 24MB they know what they're doing? This 8MB minimum strikes me as a bit opaque.

@ordian ordian Apr 11, 2019

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Actually, I agree with David, that it may be surprising for a user. Although, in practice, most of the time it only makes sense to use the default cache size or to increase it, which won't affect the maximum. I'll push a commit to remove it.

let cache = Cache::new(cache_size);
block_opts.set_cache(cache);
}
Expand Down