----- On Feb 19, 2020, at 10:47 AM, Tejun Heo tj@xxxxxxxxxx wrote: > On Wed, Feb 19, 2020 at 10:43:05AM -0500, Mathieu Desnoyers wrote: >> The regression I'm talking about here is that CONFIG_CPUSET=y changes the >> behavior of the sched_setaffinify system call, which existed prior to >> cpusets. >> >> sched_setaffinity should behave in the same way for kernels configured with >> CONFIG_CPUSET=y or CONFIG_CPUSET=n. >> >> The fact that cpuset decides to irreversibly change the task affinity mask >> may not be considered a regression if it has always done that, but changing >> the behavior of sched_setaffinity seems to fit the definition of a regression. > > We generally use "regression" for breakages which weren't in past > versions but then appeared later. It has debugging implications > because if we know something is a regression, we generally can point > to the commit which introduced the bug either through examining the > history or bisection. > > It is a silly bug, for sure, but slapping regression name on it just > confuses rather than helping anything. I can look into figuring out the commit introducing this issue, which I suspect will be close to the introduction of CONFIG_CPUSET into the kernel (which was ages ago). I'll check and let you know. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
