Re: [PATCH 0/4] futex: get_user_pages_fast() for shared futexes

From: Ulrich Drepper
Date: Tue Sep 30 2008 - 23:14:15 EST


On Tue, Sep 30, 2008 at 3:55 AM, Eric Dumazet <dada1@xxxxxxxxxxxxx> wrote:
> I am not sure how it could be converted to private futexes, since
> old binaries (static glibc) will use FUTEX_WAKE like calls.

We considered this back when but any effort seems too much. We'd
either need a clone flag (a scarce resource) or replace the set_tid
_address syscall. Given that the futex is woken once per thread
lifetime it shouldn't be an issue. If the semaphore shows up even
after this patch feel free to introduce a new set_tid_address syscall.
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