Le Wed, May 31, 2023 at 12:17:27PM +0200, Frederic Weisbecker a écrit : > Hi, > > Here is a first attempt at providing support for lazy callbacks on > non-offloaded CPUs. I have measured interesting results on my machine > when it is mostly idle (just an idle ssh connection kept alive) with > a gain of +10% idle time. This needs more serious testing though, > especially to make sure that no performance regression is introduced. So after refining my measurements, it actually doesn't seem to bring much. Here's what I measured (it's an average after 100 runs): * 0.01% more idle time during a "sleep 10" * introduce 3% performance regression during an "scp" on the tools directory of the kernel source. * Brings less than 1% performance improvement with a "make" on tools/perf It only brings unconditional improvement when rcu boost is enabled (callbacks offloaded to rcuc) but still below 1%. The reason for the performance penalty is unclear, I initially thought it was due to the batch execution delaying other softirqs vectors but it doesn't look that way after all. So for now I'm only going to re-iterate the cleanups in the beginning of the patchset and I'll wait for a good reason before ever proceeding with the rest. Thanks.
