Stream: t-compiler/wg-parallel-rustc

Topic: sharding hash quality


simulacrum (Nov 25 2019 at 16:41, on Zulip):

@Zoxc one thing I noticed this weekend is that we keep the original hash when we shard, which means that 5 bits at least of the hash are always the same within a single shard, have we checked that hashbrown is okay with that?

simulacrum (Nov 25 2019 at 16:41, on Zulip):

I know I've heard historically that hash quality is super important for the hashmap performance (particularly the one we're using)

Zoxc (Nov 25 2019 at 17:01, on Zulip):

I picked the bits which hashbrown uses last to use for sharding

simulacrum (Nov 25 2019 at 18:07, on Zulip):

sure, but the hash is still being used for the top-level selection of which element to use, right?

simulacrum (Nov 25 2019 at 18:07, on Zulip):

did we check that we're still getting a good distribution?

Last update: Dec 12 2019 at 01:05UTC