On 06/25/2012 12:19 PM, Greg Kroah-Hartman wrote:

On Mon, Jun 25, 2012 at 12:10:57PM -0500, Seth Jennings wrote:

quoted

On 06/25/2012 11:59 AM, Greg Kroah-Hartman wrote:

quoted

On Mon, Jun 25, 2012 at 11:14:37AM -0500, Seth Jennings wrote:

quoted

This patch adds generic pages mapping methods that
work on all archs in the absence of support for
local_tlb_flush_kernel_range() advertised by the
arch through __HAVE_LOCAL_TLB_FLUSH_KERNEL_RANGE

Is this #define something that other arches define now?  Or is this
something new that you are adding here?

Something new I'm adding.

Ah, ok.

quoted

The precedent for this approach is the __HAVE_ARCH_* defines
that let the arch independent stuff know if a generic
function needs to be defined or if there is an arch specific
function.

You can "grep -R __HAVE_ARCH_* arch/x86/" to see the ones
that already exist.

I guess I should have called it
__HAVE_ARCH_LOCAL_TLB_FLUSH_KERNEL_RANGE though, not
__HAVE_LOCAL_TLB_FLUSH_KERNEL_RANGE.

You need to get the mm developers to agree with this before I can take
it.

But, why even depend on this?  Can't you either live without it

The whole point of the patch is _not_ to depend on it.  It
just performs worse without it.  We could just rip out all
the the page table assisted page mapping, but, for the
arches that have support for it, we'd be degrading
performance in exchange for portability.  Why choose when we
can have both?

, or just implement it for all arches somehow?

It can be implemented for some arches and already is for
some (MIPS, ARM, at least).  But for some arches, I imagine
this can't be implemented due to hardware limitations.

A benefit of this approach is the arches opt-in to the
optimized zsmalloc by implementing
local_tlb_flush_kernel_range() without having to change
anything in zsmalloc.

--
Seth

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