Christoph Hellwig's on June 21, 2019 6:15 pm:
> On Thu, Jun 20, 2019 at 10:21:46AM -0700, Linus Torvalds wrote:
>> Hmm. Honestly, I've never seen anything like that in any kernel profiles.
>>
>> Compared to the problems I _do_ see (which is usually the obvious
>> cache misses, and locking), it mus
Linus Torvalds's on June 21, 2019 3:21 am:
> On Thu, Jun 20, 2019 at 5:19 AM Nicholas Piggin wrote:
>>
>> The processor aliasing problem happens because the struct will
>> be initialised with stores using one base register (e.g., stack
>> register), and then same memory is loaded using a different
On Thu, Jun 20, 2019 at 10:21:46AM -0700, Linus Torvalds wrote:
> Hmm. Honestly, I've never seen anything like that in any kernel profiles.
>
> Compared to the problems I _do_ see (which is usually the obvious
> cache misses, and locking), it must either be in the noise or it's
> some problem spec
On Thu, Jun 20, 2019 at 5:19 AM Nicholas Piggin wrote:
>
> The processor aliasing problem happens because the struct will
> be initialised with stores using one base register (e.g., stack
> register), and then same memory is loaded using a different
> register (e.g., parameter register).
Hmm. Hon
Linus Torvalds's on June 12, 2019 11:09 am:
> On Tue, Jun 11, 2019 at 2:55 PM Nicholas Piggin wrote:
>>
>> What does this do for performance? I've found this pattern can be
>> bad for store aliasing detection.
>
> I wouldn't expect it to be noticeable, and the lack of argument
> reloading etc sho
> On Jun 11, 2019, at 5:52 PM, Nicholas Piggin wrote:
>
> Christoph Hellwig's on June 12, 2019 12:41 am:
>> Instead of passing a set of always repeated arguments down the
>> get_user_pages_fast iterators, create a struct gup_args to hold them and
>> pass that by reference. This leads to an over
On Tue, Jun 11, 2019 at 2:55 PM Nicholas Piggin wrote:
>
> What does this do for performance? I've found this pattern can be
> bad for store aliasing detection.
I wouldn't expect it to be noticeable, and the lack of argument
reloading etc should make up for it. Plus inlining makes it a
non-issue
Christoph Hellwig's on June 12, 2019 12:41 am:
> Instead of passing a set of always repeated arguments down the
> get_user_pages_fast iterators, create a struct gup_args to hold them and
> pass that by reference. This leads to an over 100 byte .text size
> reduction for x86-64.
What does this do
Instead of passing a set of always repeated arguments down the
get_user_pages_fast iterators, create a struct gup_args to hold them and
pass that by reference. This leads to an over 100 byte .text size
reduction for x86-64.
Signed-off-by: Christoph Hellwig
---
mm/gup.c | 338 +++
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