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| author | Evan Brown <ezb@google.com> | 2024-03-19 12:07:34 -0700 |
|---|---|---|
| committer | Copybara-Service <copybara-worker@google.com> | 2024-03-19 12:08:27 -0700 |
| commit | 1980d7b98a0cae64432ccf9c4afebda5e21b2c5e (patch) | |
| tree | 89fa98715f94d4f0221080158e1c798dc5cf52c0 /absl/container/BUILD.bazel | |
| parent | 43c36ffae6256b4c93c1b9d3c73efaf8c2c891ab (diff) | |
| download | abseil-1980d7b98a0cae64432ccf9c4afebda5e21b2c5e.tar.gz abseil-1980d7b98a0cae64432ccf9c4afebda5e21b2c5e.tar.bz2 abseil-1980d7b98a0cae64432ccf9c4afebda5e21b2c5e.zip | |
Do hashtablez sampling on the first insertion into an empty SOO hashtable.
When sampling triggers, we skip SOO and allocate a backing array. We must do this because the HashtablezInfoHandle is part of the heap allocation (along with the control bytes and slots). By default, we sample 1 in ~1024 hashtables when sampling is enabled. This will impact performance because (a) we won't benefit from SOO so we would have worse data locality (more cache/TLB misses), and (b) the backing array capacity will be 3 instead of 1 so (b.1) we skip the rehash after the second insertion and (b.2) we potentially waste up to two slots worth of memory.
We also add an soo_capacity field to HashtablezInfo to allow for distinguishing which sampled tables may otherwise have been SOO - this will allow us to know approximately what fraction of tables are in SOO mode.
PiperOrigin-RevId: 617252334
Change-Id: Ib48b7a4870bd74ea3ba923ed8f350a3b75dbb7d3
Diffstat (limited to 'absl/container/BUILD.bazel')
| -rw-r--r-- | absl/container/BUILD.bazel | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/absl/container/BUILD.bazel b/absl/container/BUILD.bazel index 0de45263..c1df8d83 100644 --- a/absl/container/BUILD.bazel +++ b/absl/container/BUILD.bazel @@ -701,8 +701,10 @@ cc_test( "//absl/base:config", "//absl/base:core_headers", "//absl/base:prefetch", + "//absl/functional:function_ref", "//absl/hash", "//absl/log", + "//absl/log:check", "//absl/memory", "//absl/meta:type_traits", "//absl/strings", |