"O. Hartmann" <ohart...@zedat.fu-berlin.de> writes:

> Am Thu, 17 Sep 2015 19:00:15 +0200
> Jean-Sébastien Pédron <dumbb...@freebsd.org> schrieb:
>> Hi everyone!
>> I'm very sorry I didn't communicate at all on the i915 update project.
>> So here is a status update: since this morning, the driver builds fine.
>> I'm currently attending the XDC (X.Org Developers Conference) and don't
>> have an Intel laptop to test with me. However, Johannes Dieterich (also
>> attending the conference) offerred his help, so we will do that today.
>> Obviously, do not expect something stable in the coming couple days.
>> Thank you for your patience :)
>> To answer various questions in this thread:
>> Why does it take so much time to update? Once Konstantin committed his
>> i915 update, I was busy with non-FreeBSD activities until last July,
>> when I slowly started back to work on i915. My goal is to reduce the
>> diff with Linux as much as possible. But, as opposed to OpenBSD and
>> DragonFlyBSD, we do not use a Linux compatibility layer which would
>> dramatically ease our life.
> My concerns are speed and performance. Isn't any kind of layer consuming 
> performance -
> sometimes worse, sometimes negligible. But anyway, HPC isn't a FreeBSD 
> domain, so ...

Look at the linux spinlock layer in ofed/include/linux/spinlock.h

        #define spin_lock(_l)           mtx_lock(&(_l)->m)
        #define spin_unlock(_l)         mtx_unlock(&(_l)->m)
        #define spin_trylock(_l)        mtx_trylock(&(_l)->m)

means, that using spinlock linux layer does not have any performance
impact. I haven't read all ofed code, but most of that is just bunch of
macros and renaming stuff to use linux code without changes and no
performance impact.

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