Esben Nielsen a écrit :
On Sat, 12 May 2007, Peter Zijlstra wrote:
On Sat, 2007-05-12 at 11:27 +0200, Esben Nielsen wrote:
On Fri, 11 May 2007, Peter Zijlstra wrote:
I was toying with a scalable rw_mutex and found that it gives ~10%
reduction in
system time on ebizzy runs (without the MADV_FREE patch).
You break priority enheritance on user space futexes! :-(
The problems is that the futex waiter have to take the mmap_sem. And as
your rw_mutex isn't PI enabled you get priority inversions :-(
Do note that rwsems have no PI either.
PI is not a concern for mainline - yet, I do have ideas here though.
If PI wasn't a concern for mainline, why is PI futexes merged into the
mainline?
If you really care about futexes and mmap_sem, just use private futexes, since
they dont use mmap_sem at all.
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