On Mon, 2015-08-17 at 21:10 +0200, Christoph Hellwig wrote:
> > #include <linux/uaccess.h>
> > +#include <linux/uio.h>
> > +
>
> Can we keep this in linux/pmem.h? I'm pretty sure the stubs would need
> it as well, and even if they don't it'll keep the includes consistent.
Sure.
> > +{
> > + size_t len;
> > +
> > + len = copy_from_iter_nocache((void __force *)addr, bytes, i);
> > +
> > + /*
> > + * copy_from_iter_nocache() on x86 only uses non-temporal stores for
> > + * iovec iterators, so for other types (bvec & kvec) we must do a
> > + * cache write-back.
>
> Shouldn't we fi that?
I'm not sure - When Al make copy_from_iter_nocache() it was just a copy of
copy_from_iter(), with the iovec case changed to use
__copy_from_user_nocache(). The other cases use memcpy_from_page() and
memcpy(). To have everything do non-temporal stores we'd probably need to
make non-temporal versions of each of those (alluded to by Al's comment in the
copy_from_iter_nocache() commit: "BTW, do we want memcpy_nocache()?").
> > + */
> > + if (iter_is_iovec(i) == false)
> > + __arch_wb_cache_pmem(addr, bytes);
>
> And if not and iter_needs_pmem_wb helper to encode this knowledge would
> be useful.
Maybe this should be the short-term solution, and I'll add a TODO to fix the
copy_from_iter_nocache() implementation as described above so we can always
have non-temporal stores?
> > +static inline void arch_clear_pmem(void __pmem *addr, size_t size)
> > +{
> > + /* TODO: implement the zeroing via non-temporal writes */
> > + if (size == PAGE_SIZE && ((unsigned long)addr & ~PAGE_MASK) == 0)
> > + clear_page((void __force *)addr);
> > + else
> > + memset((void __force *)addr, 0, size);
> > +
> > + __arch_wb_cache_pmem(addr, size);
>
> Please add a local vaiable so that the __force casting is only needed
> once. Same for other functions with this pattern.
Sure.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
