@4moonsettler@L0RINC@andrew_s_toth Itβll take a few more days to finish the re-testing, but it seems to me that this slowdown has nothing to do with LevelDB. The disk reads are coming from the files blk/rev*.dat. For some reason, those files arenβt staying in RAM the way they do with the default dbcache setting.
Can someone explain this?
IBD with a +10GB dbcache runs fine until ~820k blocks, then disk reads suddenly explode and I/O becomes the bottleneck.
If the cache is supposed to prevent this, why does it happen right there?
#Bitcoin#Benchmark#Performance
@4moonsettler@L0RINC@andrew_s_toth I'm rerunning all the tests, and this time I'm logging all the activity (vmstat, iostat, and iotop) with timestamps so I can create several graphs showing disk and memory usage.
@L0RINC@murchandamus@andrew_s_toth The performance level I'm using is Balanced. Let's assume that's the cause - in that case, shouldn't I also see the same bottleneck during IBD with dbcache=1024 starting from block ~820,000 onwards, like I do with higher dbcache values?
https://t.co/rEX8zjUDVq
@L0RINC@andrew_s_toth@4moonsettler I'm trying to understand this performance discrepancy between different dbcache values and why this bottleneck occurs with dbcache=10240 when there's still plenty of free memory available.
@andrew_s_toth@4moonsettler I don't think it's a disk performance limitation. If it were, I'd expect it to be present throughout the entire process, not only starting around block ~820,000.
Also, with more memory available for "dbcache", shouldn't disk usage be significantly lower?
@L0RINC I assume that warning only appears when "dbcache" is configured higher than the total amount of RAM available. With 24 GB of RAM, "dbcache=10 GB" should work fine.
The only warnings I ran into were these:
@4moonsettler@andrew_s_toth I didn't get a chance to generate the disk I/O graph, but I do have this screenshot from when I first started noticing the excessive disk usage.
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#Bitcoin Core v31.0
IBD completed in ~24h50m on:
- Ubuntu 24.04 ARM64
- Oracle Cloud Ampere A1
- 4 OCPU / 24GB RAM
- 200GB SSD
600+ peers during sync.
Obs: Tor/I2P peers rarely stayed connected for more than ~10 min during IBD due to lower throughput compared to IPv4 peers.