I will try your idea after it finishes to generate DB 77 in about 7 days

But :
DB 75 → extend to 85: 2^(85-75) = 1024 partitions
DB 77 → extend to 85: 2^(85-77) = 256 partitions
4× less partitions -> 4× faster
Partitions for puzzle 85 Median time for puzzle 85
DB 75 1024 ~1 min
DB 77 256 ~15 sec
So .... DB 77 with 2^31 > DB 85 with 2^30 (2× faster)
You are right but at equal entries, DB 85 is better than DB 77, zero overhead.
But I have 2^31 in DB 77, so double.
I tried to save the first 2^30 DPs instead of the first 2^29 DPs (always 74-75 range),
4GB+8GB instead of 2GB + 4GB,
workers x batch = 192x60, aws machine, test of only 30 keys in range
84-85==========================================================
SUMMARY
==========================================================
Total keys: 30
Solved: 30
Failed/Aborted: 0
Total time: 886.2s
Min: 2.531s | Max: 102.924s
Mean time/key:
29.541s >>> MEDIAN:
18.446s <<<
Mean steps/key: 28566.83M
Median steps: 17692.83M
StdDev: 26402.86M
95% CI (mean): [19118.68M, 38014.97M] steps/key
==========================================================
It's okay?
Half of the keys in 18s or less.
I modified the kangaroo-wild so it can work in -ssd mode, only 2GB in ram and the db_file on ssd.
I wonder how fast could be if I save the first 2^31 or the first 2^32 DPs ....

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EDIT:
I tried to find a few keys in
89-90 range, I was very lucky for the first key:
[!!!] KEY FOUND (f1 m1/1 delta=1454 partition=29075): 0x7d4ac6516f11e2b19fc
[SOLVED 1/5] Key: 0x3c64fd4ac6516f11e2b19fc (part 29075) | Steps: 109917.3M | Time:
114.930sbut not for the second one:
[!!!] KEY FOUND (f2 m1/1 delta=1353 partition=11682): 0x78b3fbfe9d14076b71b
[SOLVED 2/5] Key: 0x2b68b8b3fbfe9d14076b71b (part 11682) | Steps: 1911265.6M | Time:
2011.398s[!!!] KEY FOUND (f1 m1/1 delta=1522 partition=29993): 0x787b34cce1255fb4266
[SOLVED 3/5] Key: 0x3d4a787b34cce1255fb4266 (part 29993) | Steps: 524447.9M | Time:
555.927s[!!!] KEY FOUND (f1 m1/1 delta=1285 partition=30439): 0x4a5b3be06a8e939e486
[SOLVED 4/5] Key: 0x3db9ca5b3be06a8e939e486 (part 30439) | Steps: 47841.3M | Time:
48.957s[!!!] KEY FOUND (f1 m1/1 delta=173 partition=15753): 0x5c4a1bd78b791cbf856
[SOLVED 5/5] Key: 0x2f625c4a1bd78b791cbf856 (part 15753) | Steps: 250001.7M | Time:
261.958s==========================================================
SUMMARY
==========================================================
Total keys: 5
Solved: 5
Failed/Aborted: 0
Total time: 2993.7s
Min: 49.058s | Max: 2011.499s
Mean time/key:
598.735s >>> MEDIAN:
262.061s <<<
Mean steps/key: 568694.78M
Median steps: 250001.73M
StdDev: 772622.91M
95% CI (mean): [0.00M, 1245928.62M] steps/key
==========================================================
I think that the real average time must be over 900s.
In any case under a 1 hour using only cpus and a database build for 74-75 bit range is not bad at all.
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My github account is ok now, I'm planning to update kangaroo-wild with -ssd option and to add in the readme file the links to
75_scored_16_30_tame_db.bin
75_scored_16_30_bucket_offsets.bin
75_scored_16_30_fingerprints.bin
75_training_16_30_params.bin
where:
75 means: 74-75 range
16 means: DP mask
30 means: 2^30 DP saved