[pbs-devel] [PATCH proxmox-backup] backup/verify: improve speed by sorting chunks by inode
Dominik Csapak
d.csapak at proxmox.com
Tue Apr 13 16:35:36 CEST 2021
before reading the chunks from disk in the order of the index file,
stat them first and sort them by inode number.
this can have a very positive impact on read speed on spinning disks,
even with the additional stat'ing of the chunks.
memory footprint should be tolerable, for 1_000_000 chunks
we need about ~16MiB of memory (Vec of 64bit position + 64bit inode)
(assuming 4MiB Chunks, such an index would reference 4TiB of data)
two small benchmarks (single spinner, ext4) here showed an improvement from
~430 seconds to ~330 seconds for a 32GiB fixed index
and from
~160 seconds to ~120 seconds for a 10GiB dynamic index
Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
it would be great if other people could also benchmark this patch on
different setups a little (in addition to me), to verify or disprove my results
src/backup/datastore.rs | 5 +++++
src/backup/verify.rs | 32 +++++++++++++++++++++++++++++---
2 files changed, 34 insertions(+), 3 deletions(-)
diff --git a/src/backup/datastore.rs b/src/backup/datastore.rs
index 28dda7e7..8162c269 100644
--- a/src/backup/datastore.rs
+++ b/src/backup/datastore.rs
@@ -686,6 +686,11 @@ impl DataStore {
}
+ pub fn stat_chunk(&self, digest: &[u8; 32]) -> Result<std::fs::Metadata, Error> {
+ let (chunk_path, _digest_str) = self.chunk_store.chunk_path(digest);
+ std::fs::metadata(chunk_path).map_err(Error::from)
+ }
+
pub fn load_chunk(&self, digest: &[u8; 32]) -> Result<DataBlob, Error> {
let (chunk_path, digest_str) = self.chunk_store.chunk_path(digest);
diff --git a/src/backup/verify.rs b/src/backup/verify.rs
index ac4a6c29..9173bd9d 100644
--- a/src/backup/verify.rs
+++ b/src/backup/verify.rs
@@ -159,13 +159,16 @@ fn verify_index_chunks(
}
);
- for pos in 0..index.index_count() {
+ let index_count = index.index_count();
+ let mut chunk_list = Vec::with_capacity(index_count);
+ use std::os::unix::fs::MetadataExt;
+
+ for pos in 0..index_count {
verify_worker.worker.check_abort()?;
crate::tools::fail_on_shutdown()?;
let info = index.chunk_info(pos).unwrap();
- let size = info.size();
if verify_worker.verified_chunks.lock().unwrap().contains(&info.digest) {
continue; // already verified
@@ -178,15 +181,38 @@ fn verify_index_chunks(
continue;
}
+ match verify_worker.datastore.stat_chunk(&info.digest) {
+ Err(err) => {
+ verify_worker.corrupt_chunks.lock().unwrap().insert(info.digest);
+ task_log!(verify_worker.worker, "can't verify chunk, stat failed - {}", err);
+ errors.fetch_add(1, Ordering::SeqCst);
+ rename_corrupted_chunk(verify_worker.datastore.clone(), &info.digest, &verify_worker.worker);
+ }
+ Ok(metadata) => {
+ chunk_list.push((pos, metadata.ino()));
+ }
+ }
+ }
+
+ chunk_list.sort_unstable_by(|(_, ino_a), (_, ino_b)| {
+ ino_a.cmp(&ino_b)
+ });
+
+ for (pos, _) in chunk_list {
+ verify_worker.worker.check_abort()?;
+ crate::tools::fail_on_shutdown()?;
+
+ let info = index.chunk_info(pos).unwrap();
+
match verify_worker.datastore.load_chunk(&info.digest) {
Err(err) => {
verify_worker.corrupt_chunks.lock().unwrap().insert(info.digest);
task_log!(verify_worker.worker, "can't verify chunk, load failed - {}", err);
errors.fetch_add(1, Ordering::SeqCst);
rename_corrupted_chunk(verify_worker.datastore.clone(), &info.digest, &verify_worker.worker);
- continue;
}
Ok(chunk) => {
+ let size = info.size();
read_bytes += chunk.raw_size();
decoder_pool.send((chunk, info.digest, size))?;
decoded_bytes += size;
--
2.20.1
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