Re: problems in commit 2d4dc890b5c8 (block: add helpers to run flush_dcache_page() against a bio and a request's pages)

[Ilya Loginov <isloginov@gmail.com>]

On Wed, 09 Dec 2009 17:47:51 -0600
James Bottomley <James.Bottomley@HansenPartnership.com> wrote:

> Which architecture is this? ... because if it's missing a necessary
> definition for flush_kernel_dcache_page() it's very easy to add it ...

This is a MIPS. Why? The call flush_dcache_page() on MIPS is lazy enought.
And it do exactly what i need to fix the problem.

> > But. I could do that rq_flush_dcache_pages will call flush_kernel_dcache_page
> > for architectures where ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE was defined.
> 
> The point I'm trying to make is that flush_dcache_page() does a lot of
> unnecessary flushing.  Where you are in the system with the READ call,
> you know the user aliases are clean (because users aren't allowed to
> touch pages submitted for write), so you only (for efficiency) need to
> flush the dirty kernel alias.

I understand that in your case(parisc) solution with flushdcache_page()
is very voracious. But I don't think that we should change something
somewhere else except parisc. Or we should write to Ralf Baechle and
other maintainers and discuss all with them. Don't think?

-- 
Ilya Loginov <isloginov@gmail.com>