Messages in this thread | | | Date | Fri, 10 May 2002 16:17:29 -0700 | From | Andrew Morton <> | Subject | Re: fs/locks.c BKL removal |
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Dave Hansen wrote: > > As Linus pointed out, a semaphore is probably the wrong way to go. > The only things that really needs to be protected are the list > operations themselves. >
It was I who put the BKL back into locks.c, much to Matthew's disgust...
The problem was that replacing the BKL with a semaphore seriously damaged Apache thoughput on 8-way. Apache was using flock()-based synchronisation and replacing a spin with a schedule just killed it.
So.. Apache isn't doing that any more, but it is an instructive case. Replacing the BKL with a semaphore can sometimes be a very bad thing.
See http://www.uwsg.iu.edu/hypermail/linux/kernel/0010.3/ - search for "scalability"
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