Post Syndicated from corbet original https://lwn.net/Articles/939973/

The big kernel lock (BKL) is a distant memory now but, for years, it was
one of the more intractable problems faced by the kernel development
community. The end of the BKL does not mean that the kernel is without
problematic locks, however. In recent times, some attention has been paid
to the software-interrupt (or “bottom half”) lock, which can create latency
problems, especially on realtime systems. Frederic Weisbecker is taking a
new tack in his campaign to cut this lock down to size, with an approach
based on how the BKL was eventually removed.