The HyperNews Linux KHG Discussion Pages


Forum: Device Drivers
Re: Question What does mark_bh() do? (Erik Petersen)
Keywords: network drivers interrupt mark_bh
Date: Fri, 14 Mar 1997 08:28:12 GMT
From: Praveen Dwivedi <>

I am not an expert on Linux kernel but here is what my
hacking wisdom says. 

mark_bh marks the bottom half of some hardware interrupts.
An example would be timer interrupt which comes 
100 times a second. Generally what happens is that you
do minimum stuff in actual handler and call mark_bh() 
which takes care of updating lots of time related system
stuff. The reason why this is the preferred way to do
things is because you want to have actual interrupt handler
as small as possible so as to avoid losing further interrupts.
Look at the code in do_timer. It may help.