On Thu, Oct 15, 2020 at 02:20:36PM -0700, Ankur Arora wrote:
> The case I was thinking of was that clear_huge_page()
That loop in clear_gigantic_page() there could be optimized not to
iterate over the pages but do a NTA moves in one go, provided they're
contiguous.
> or faultin_page() would
faul
On 2020-10-15 3:40 a.m., Borislav Petkov wrote:
On Wed, Oct 14, 2020 at 08:21:57PM -0700, Ankur Arora wrote:
Also, if we did extend clear_page() to take the page-size as parameter
we still might not have enough information (ex. a 4K or a 2MB page that
clear_page() sees could be part of a GUP of
On 2020-10-15 3:35 a.m., Borislav Petkov wrote:
On Wed, Oct 14, 2020 at 08:37:44PM -0700, Ankur Arora wrote:
I don't disagree but I think the selection of cached/uncached route should
be made where we have enough context available to be able to choose to do
this.
This could be for example, done
On Wed, Oct 14, 2020 at 08:21:57PM -0700, Ankur Arora wrote:
> Also, if we did extend clear_page() to take the page-size as parameter
> we still might not have enough information (ex. a 4K or a 2MB page that
> clear_page() sees could be part of a GUP of a much larger extent) to
> decide whether to
On Wed, Oct 14, 2020 at 08:37:44PM -0700, Ankur Arora wrote:
> I don't disagree but I think the selection of cached/uncached route should
> be made where we have enough context available to be able to choose to do
> this.
>
> This could be for example, done in mm_populate() or gup where if say the
On 2020-10-14 2:12 p.m., Borislav Petkov wrote:
On Wed, Oct 14, 2020 at 02:07:30PM -0700, Andy Lutomirski wrote:
I assume it’s for a little optimization of clearing more than one
page per SFENCE.
In any event, based on the benchmark data upthread, we only want to do
NT clears when they’re rathe
On 2020-10-14 2:07 p.m., Andy Lutomirski wrote:
On Oct 14, 2020, at 12:58 PM, Borislav Petkov wrote:
On Wed, Oct 14, 2020 at 08:45:37AM -0700, Andy Lutomirski wrote:
On Wed, Oct 14, 2020 at 1:33 AM Ankur Arora wrote:
Define clear_page_uncached() as an alternative_call() to clear_page_nt
> On Oct 14, 2020, at 12:58 PM, Borislav Petkov wrote:
>
> On Wed, Oct 14, 2020 at 08:45:37AM -0700, Andy Lutomirski wrote:
>>> On Wed, Oct 14, 2020 at 1:33 AM Ankur Arora
>>> wrote:
>>>
>>> Define clear_page_uncached() as an alternative_call() to clear_page_nt()
>>> if the CPU sets X86_F
On Wed, Oct 14, 2020 at 02:07:30PM -0700, Andy Lutomirski wrote:
> I assume it’s for a little optimization of clearing more than one
> page per SFENCE.
>
> In any event, based on the benchmark data upthread, we only want to do
> NT clears when they’re rather large, so this shouldn’t be just an
> al
On 2020-10-14 8:45 a.m., Andy Lutomirski wrote:
On Wed, Oct 14, 2020 at 1:33 AM Ankur Arora wrote:
Define clear_page_uncached() as an alternative_call() to clear_page_nt()
if the CPU sets X86_FEATURE_NT_GOOD and fallback to clear_page() if it
doesn't.
Similarly define clear_page_uncached_flus
On Wed, Oct 14, 2020 at 08:45:37AM -0700, Andy Lutomirski wrote:
> On Wed, Oct 14, 2020 at 1:33 AM Ankur Arora wrote:
> >
> > Define clear_page_uncached() as an alternative_call() to clear_page_nt()
> > if the CPU sets X86_FEATURE_NT_GOOD and fallback to clear_page() if it
> > doesn't.
> >
> > Sim
On Wed, Oct 14, 2020 at 1:33 AM Ankur Arora wrote:
>
> Define clear_page_uncached() as an alternative_call() to clear_page_nt()
> if the CPU sets X86_FEATURE_NT_GOOD and fallback to clear_page() if it
> doesn't.
>
> Similarly define clear_page_uncached_flush() which provides an SFENCE
> if the CPU
Hi Ankur,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on tip/master]
[also build test ERROR on linus/master next-20201013]
[cannot apply to tip/x86/core linux/master v5.9]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting pat
Hi Ankur,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on tip/master]
[also build test ERROR on linus/master next-20201013]
[cannot apply to tip/x86/core linux/master v5.9]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting pat
Define clear_page_uncached() as an alternative_call() to clear_page_nt()
if the CPU sets X86_FEATURE_NT_GOOD and fallback to clear_page() if it
doesn't.
Similarly define clear_page_uncached_flush() which provides an SFENCE
if the CPU sets X86_FEATURE_NT_GOOD.
Also, add the glue interface clear_us
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