Even with radiators and fans, a system’s CPUs can overheat. When that
happens, the kernel’s thermal governor will cap the maximum frequency of
that CPU to
allow it to cool. The scheduler, however, is not aware that the CPU’s
capacity has changed; it may schedule more work than optimal in the current
conditions, leading to a performance degradation. Recently, Thara
Gopinath did
some research and posted a patch set to address this problem. The
solution adds an interface to inform the scheduler about thermal events so
that it can assign tasks better and thus improve the overall system
performance.

Source: LWN.net – [$] Telling the scheduler about thermal pressure