Positive to negative ratio [LWN.net]

Positive to negative ratio

Posted Jul 7, 2026 18:28 UTC (Tue) by jmgao (subscriber, #104246)
In reply to: Positive to negative ratio by kleptog
Parent article: Limiting negative dentries

> I would think that if a negative dentry hasn't been hit in the last minute you can probably toss it.

The compiler include use case is going to be pretty disconnected from any wall-clock time, since the iteration time of an edit-compile-test loop is going to be highly variable.

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Positive to negative ratio

Posted Jul 7, 2026 19:10 UTC (Tue) by rgmoore (✭ supporter ✭, #75) [Link]

The issue with compiling is when you have to compile many individual .c files, each of which has the same set of includes. It makes sense to cache that information so you don't have to perform the same expensive file checks again for each .c file. When you get into the test and edit steps of the loop, you can safely flush the cache. It's going to be a really long time before you need to look that information up again, and the cache will repopulate as soon as you compile one file.