Am 08.04.25 um 22:56 schrieb Norbert:
Hi,
Am 08.04.25 um 12:32 schrieb Ondřej Kuzník:
just a thought:
It looks like you also have a "sub"string index on that attribute, all
indexes for a given attribute exist in the same namespace and a
substring index generates a *lot* of items. So you'll get false
positives competing for slapd's attention - have you enabled 64bit
hashes already ("index_hash64 on")?
Should help with the contention if you haven't yet.
I did two further tests:
1) olcIndexHash64: TRUE
2) olcIndexHash64: TRUE and only keeping eq for almost_uniqe_attr
in both cases config and data was wiped and re-created with slapadd
I confirmed that keysize is now 64bit in the index.
mdb_stat for the index with eq,sub and 32bit index keys from a running server
Status of almost_uniqe_attr
Tree depth: 3
Branch pages: 256
Leaf pages: 47269
Overflow pages: 0
Entries: 47486472
mdb_stat for index with eq only and 64bit index keys after fresh import
Status of almost_uniqe_attr
Tree depth: 4
Branch pages: 261
Leaf pages: 41908
Overflow pages: 0
Entries: 3931262
Unfortunately there was no change in runtime. The 1200 queries still take
around 11s, might be even a tiny bit
slower with 12s.
When running those 1200 filters and recording activity with perf in parallel I
get at the top
# Samples: 45K of event 'cpu-clock:pppH'
# Event count (approx.): 11330500000
#
# Children Self Command Shared Object Symbol
# ........ ........ ....... .......................
.............................................
#
41.12% 40.82% slapd back_mdb-2.5.so.0.1.14 [.] mdb_idl_next
|
---mdb_idl_next
31.71% 31.55% slapd back_mdb-2.5.so.0.1.14 [.] mdb_idl_intersection
|
---mdb_idl_intersection
24.25% 24.11% slapd back_mdb-2.5.so.0.1.14 [.] mdb_idl_next@plt
|
---mdb_idl_next@plt
1.13% 0.00% slapd [kernel.kallsyms] [k]
entry_SYSCALL_64_after_hwframe
|
---entry_SYSCALL_64_after_hwframe
|
And when removing the second entry I get for the same 1200 filters following
recorded
# Samples: 420 of event 'cpu-clock:pppH'
# Event count (approx.): 105000000
#
# Children Self Command Shared Object Symbol
# ........ ........ ....... .......................
.......................................
#
41.90% 0.00% slapd [kernel.kallsyms] [k]
entry_SYSCALL_64_after_hwframe
|
---entry_SYSCALL_64_after_hwframe
|
|--41.19%--do_syscall_64
| |
| |--22.62%--ksys_write
Thanks,
Norbert
