tree acab84593c38bfc65b2a40497eac8772b2438da9
parent 39c03fb65268e3331f381714c664a581a6e86b8c
parent 8abafd085aab9b703711b49d02b66910c8c2d739
author bors <bors@rust-lang.org> 1685286453 +0000
committer bors <bors@rust-lang.org> 1685286453 +0000

Auto merge of #111755 - Zoxc:sharded-switch, r=cjgillot

Use only one shard with a single thread

This changes `Sharded` to only access a single shard using a mask set to `0` when a single thread is used, which leads to cache utilization improvements.

Performance improvement with 1 thread and `cfg(parallel_compiler)`:
<table><tr><td rowspan="2">Benchmark</td><td colspan="1"><b>Before</b></th><td colspan="2"><b>After</b></th></tr><tr><td align="right">Time</td><td align="right">Time</td><td align="right">%</th></tr><tr><td>🟣 <b>clap</b>:check</td><td align="right">1.7402s</td><td align="right">1.7004s</td><td align="right">💚  -2.29%</td></tr><tr><td>🟣 <b>hyper</b>:check</td><td align="right">0.2633s</td><td align="right">0.2550s</td><td align="right">💚  -3.12%</td></tr><tr><td>🟣 <b>regex</b>:check</td><td align="right">0.9716s</td><td align="right">0.9482s</td><td align="right">💚  -2.41%</td></tr><tr><td>🟣 <b>syn</b>:check</td><td align="right">1.5679s</td><td align="right">1.5358s</td><td align="right">💚  -2.05%</td></tr><tr><td>🟣 <b>syntex_syntax</b>:check</td><td align="right">6.0569s</td><td align="right">5.9272s</td><td align="right">💚  -2.14%</td></tr><tr><td>Total</td><td align="right">10.5999s</td><td align="right">10.3666s</td><td align="right">💚  -2.20%</td></tr><tr><td>Summary</td><td align="right">1.0000s</td><td align="right">0.9760s</td><td align="right">💚  -2.40%</td></tr></table>

cc `@SparrowLii`