The Big Kernel Lock lives on

The Big Kernel Lock lives on

Posted May 27, 2004 11:24 UTC (Thu) by kunitz (guest, #3965)
In reply to: The Big Kernel Lock lives on by ncm
Parent article: The Big Kernel Lock lives on

Alan Cox, I believe, emphasized: Locks protect data; not threads. As long as two threads don't access the same data, they are not required to share the same lock. Today most of the kernel data is protected by granular locks; however there is still data protected by the big kernel lock. So finding all the users of the big kernel lock is the easy part, you must find out which data is actually protected and you must introduce granular locks to protect that data.

Even in the pre-SMP times you had to lock data against interrupt handlers. Linus simply disabled and enabled interrupts in the critical sections using the infamous cli()/sti() pairs. I believe, the simplicity of that solution inspired the big kernel lock.

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