Hi,
On Sat, 16 Nov 2002 19:30:03 +0100
Andi Kleen <ak@suse.de> mentioned:
>
> The proper way to save it is to use kernel_fpu_begin()
Thanks! I will look into it. This is what I was looking for.
I been running this kernel with my copy for three days, and never had
oops, but I was really worried.
> > > Also I'm pretty sure that using movntq (= forcing destination out of
> > > cache) is not a good strategy for generic copy_from_user(). It may
> > > be a win for the copies in write ( user space -> page cache ),
> >
> > Yes, that why I included postfetch in the code because movntq does not leave
> > them in the L2 cache.
>
> That looks rather wasteful - first force it out and then trying to get it in
> again. I have my doubts on it being a good strategy for speed.
It tried both, use just normal mov or movq <-> use movntq + postfetch, and the later
was much much faster, because postfetch needs to read only every 64 bytes.
I will ckeck kernel_fpu_begin() fisrt and if using fpu register is too much
overhead than I will remove them.
Akira
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Sat Nov 23 2002 - 22:00:17 EST