Re: [RFC] New locking primitive for 2.5

Alexander Viro
2002-02-08T19:11:04Z

On Fri, 8 Feb 2002, Ingo Molnar wrote:

> > I'm going to send ext2-without-BKL patches to Linus - tonight or
> > tomorrow. I really wonder what effect that would have on the things.
>
> oh, that is a really cool thing!
>
> llseek() is unrelated, and i think pretty gross. Is there any other reason
> to llseek()'s i_sem usage other than the 64-bit atomic update of the file
> offset value? We can do lockless, SMP-correct 64-bit updates on x86 pretty
> easily.

Umm... Wait a second. You've seen the problems on ->i_sem variant
of llseek()? My apologies - I've misparsed you.

I seriously suspect that BKL-for-lseek() will be good enough once we
kill BKL in ext2_get_block() and friends. IOW, I doubt that
generic_file_lseek() showing up in BKL contention is the real
problem...