Chaining hash table for repository.Index

These are faster to construct but slower to access. The allocation rate
is halved, the peak memory usage almost halved compared to standard map.

Benchmark results on linux/amd64, -benchtime=3s -count=20:

name                                            old time/op    new time/op    delta
PackerManager-8                                    178ms ± 0%     178ms ± 0%     ~     (p=0.231 n=20+20)
DecodeIndex-8                                      4.54s ± 0%     4.30s ± 0%   -5.20%  (p=0.000 n=18+17)
DecodeIndexParallel-8                              4.54s ± 0%     4.30s ± 0%   -5.22%  (p=0.000 n=19+18)
IndexHasUnknown-8                                 44.4ns ± 5%    50.5ns ±11%  +13.82%  (p=0.000 n=19+17)
IndexHasKnown-8                                   48.3ns ± 0%    51.5ns ±12%   +6.68%  (p=0.001 n=16+20)
IndexAlloc-8                                       758ms ± 1%     616ms ± 1%  -18.69%  (p=0.000 n=19+19)
IndexAllocParallel-8                               234ms ± 3%     204ms ± 2%  -12.60%  (p=0.000 n=20+18)
MasterIndexLookupSingleIndex-8                     122ns ± 0%     145ns ± 9%  +18.44%  (p=0.000 n=14+20)
MasterIndexLookupMultipleIndex-8                   369ns ± 2%     429ns ± 8%  +16.27%  (p=0.000 n=20+20)
MasterIndexLookupSingleIndexUnknown-8             68.4ns ± 5%    74.9ns ±13%   +9.47%  (p=0.000 n=20+20)
MasterIndexLookupMultipleIndexUnknown-8            315ns ± 3%     369ns ±11%  +17.14%  (p=0.000 n=20+20)
MasterIndexLookupParallel/known,indices=5-8        743ns ± 1%     816ns ± 2%   +9.87%  (p=0.000 n=17+17)
MasterIndexLookupParallel/unknown,indices=5-8      238ns ± 1%     260ns ± 2%   +9.14%  (p=0.000 n=19+20)
MasterIndexLookupParallel/known,indices=10-8      1.01µs ± 3%    1.11µs ± 2%   +9.79%  (p=0.000 n=19+20)
MasterIndexLookupParallel/unknown,indices=10-8     222ns ± 0%     269ns ± 2%  +20.83%  (p=0.000 n=16+20)
MasterIndexLookupParallel/known,indices=20-8      1.06µs ± 2%    1.19µs ± 2%  +12.95%  (p=0.000 n=19+18)
MasterIndexLookupParallel/unknown,indices=20-8     413ns ± 1%     530ns ± 1%  +28.19%  (p=0.000 n=18+20)
SaveAndEncrypt-8                                  30.2ms ± 1%    30.4ms ± 0%   +0.71%  (p=0.000 n=19+19)
LoadTree-8                                         540µs ± 1%     576µs ± 1%   +6.73%  (p=0.000 n=20+20)
LoadBlob-8                                        5.64ms ± 0%    5.64ms ± 0%     ~     (p=0.883 n=18+17)
LoadAndDecrypt-8                                  5.93ms ± 0%    5.95ms ± 1%     ~     (p=0.247 n=20+19)
LoadIndex-8                                       25.1ms ± 0%    24.5ms ± 1%   -2.54%  (p=0.000 n=18+17)

name                                            old speed      new speed      delta
PackerManager-8                                  296MB/s ± 0%   296MB/s ± 0%     ~     (p=0.229 n=20+20)
SaveAndEncrypt-8                                 139MB/s ± 1%   138MB/s ± 0%   -0.71%  (p=0.000 n=19+19)
LoadBlob-8                                       177MB/s ± 0%   177MB/s ± 0%     ~     (p=0.890 n=18+17)
LoadAndDecrypt-8                                 169MB/s ± 0%   168MB/s ± 1%     ~     (p=0.227 n=20+19)

name                                            old alloc/op   new alloc/op   delta
PackerManager-8                                   91.8kB ± 0%    91.8kB ± 0%     ~     (p=0.772 n=12+19)
IndexAlloc-8                                       786MB ± 0%     400MB ± 0%  -49.04%  (p=0.000 n=20+18)
IndexAllocParallel-8                               786MB ± 0%     401MB ± 0%  -49.04%  (p=0.000 n=19+15)
SaveAndEncrypt-8                                  21.0MB ± 0%    21.0MB ± 0%   +0.00%  (p=0.000 n=19+19)

name                                            old allocs/op  new allocs/op  delta
PackerManager-8                                    1.41k ± 0%     1.41k ± 0%     ~     (all equal)
IndexAlloc-8                                        977k ± 0%      907k ± 0%   -7.18%  (p=0.000 n=20+20)
IndexAllocParallel-8                                977k ± 0%      907k ± 0%   -7.17%  (p=0.000 n=19+15)
SaveAndEncrypt-8                                    73.0 ± 0%      73.0 ± 0%     ~     (all equal)
This commit is contained in:
greatroar
2020-06-23 22:13:25 +02:00
parent 255ba83c4b
commit 7bda28f31f
7 changed files with 395 additions and 118 deletions

View File

@@ -1,6 +1,8 @@
Enhancement: Reduce memory consumption of in-memory index
We've improved how the index is stored in memory.
This change reduces memory usage for large repositories by about 30-40%.
This change can reduce memory usage for large repositories by up to 50%
(depending on the operation).
https://github.com/restic/restic/pull/2781
https://github.com/restic/restic/pull/2812