From: Li, Aubrey
> Sent: 13 November 2018 13:07
...
> > Isn't there an obvious optimisation to execute VZEROALL during system call
> > entry?
>
> I'm not aware of this in the kernel, maybe you are talking about some
> optimization in glibc?
I've not seen it anywhere either.
IIRC all the xmm and
From: Li, Aubrey
> Sent: 13 November 2018 13:07
...
> > Isn't there an obvious optimisation to execute VZEROALL during system call
> > entry?
>
> I'm not aware of this in the kernel, maybe you are talking about some
> optimization in glibc?
I've not seen it anywhere either.
IIRC all the xmm and
On 2018/11/13 18:25, David Laight wrote:
> From: Li, Aubrey
>> Sent: 12 November 2018 01:41
> ...
>> VZEROUPPER instruction resets the init state. If context switch happens
>> to occur exactly after VZEROUPPER instruction, XINUSE bitmap is empty(all
>> zeros), which indicates the task is not using
On 2018/11/13 18:25, David Laight wrote:
> From: Li, Aubrey
>> Sent: 12 November 2018 01:41
> ...
>> VZEROUPPER instruction resets the init state. If context switch happens
>> to occur exactly after VZEROUPPER instruction, XINUSE bitmap is empty(all
>> zeros), which indicates the task is not using
From: Li, Aubrey
> Sent: 12 November 2018 01:41
...
> VZEROUPPER instruction resets the init state. If context switch happens
> to occur exactly after VZEROUPPER instruction, XINUSE bitmap is empty(all
> zeros), which indicates the task is not using AVX. That's why the state
> decay count is used
From: Li, Aubrey
> Sent: 12 November 2018 01:41
...
> VZEROUPPER instruction resets the init state. If context switch happens
> to occur exactly after VZEROUPPER instruction, XINUSE bitmap is empty(all
> zeros), which indicates the task is not using AVX. That's why the state
> decay count is used
On 2018/11/12 23:46, Dave Hansen wrote:
> On 11/11/18 9:38 PM, Li, Aubrey wrote:
>
>>> Do we want this, or do we want something more time-based?
>>>
>> This counter is introduced here to solve the race of context switch and
>> VZEROUPPER. 3 context switches mean the same thread is on-off CPU 3
On 2018/11/12 23:46, Dave Hansen wrote:
> On 11/11/18 9:38 PM, Li, Aubrey wrote:
>
>>> Do we want this, or do we want something more time-based?
>>>
>> This counter is introduced here to solve the race of context switch and
>> VZEROUPPER. 3 context switches mean the same thread is on-off CPU 3
Hi Dave,
Thanks for your comments!
On 2018/11/12 10:32, Dave Hansen wrote:
> On 11/7/18 9:16 AM, Aubrey Li wrote:
>> XSAVES and its variants use init optimization to reduce the amount of
>> data that they save to memory during context switch. Init optimization
>> uses the state component bitmap
Hi Dave,
Thanks for your comments!
On 2018/11/12 10:32, Dave Hansen wrote:
> On 11/7/18 9:16 AM, Aubrey Li wrote:
>> XSAVES and its variants use init optimization to reduce the amount of
>> data that they save to memory during context switch. Init optimization
>> uses the state component bitmap
On 11/7/18 9:16 AM, Aubrey Li wrote:
> XSAVES and its variants use init optimization to reduce the amount of
> data that they save to memory during context switch. Init optimization
> uses the state component bitmap to denote if a component is in its init
> configuration. We use this information
On 11/7/18 9:16 AM, Aubrey Li wrote:
> XSAVES and its variants use init optimization to reduce the amount of
> data that they save to memory during context switch. Init optimization
> uses the state component bitmap to denote if a component is in its init
> configuration. We use this information
On 2018/11/9 19:21, Thomas Gleixner wrote:
> Aubrey,
>
> On Thu, 8 Nov 2018, Aubrey Li wrote:
>
>> Subject: x86/fpu: detect AVX task
>
> What is an AVX task? I know what you mean, but for the casual reader this
> is not very informative. So something like:
>
> x86/fpu: Track AVX usage
On 2018/11/9 19:21, Thomas Gleixner wrote:
> Aubrey,
>
> On Thu, 8 Nov 2018, Aubrey Li wrote:
>
>> Subject: x86/fpu: detect AVX task
>
> What is an AVX task? I know what you mean, but for the casual reader this
> is not very informative. So something like:
>
> x86/fpu: Track AVX usage
Aubrey,
On Thu, 8 Nov 2018, Aubrey Li wrote:
> Subject: x86/fpu: detect AVX task
What is an AVX task? I know what you mean, but for the casual reader this
is not very informative. So something like:
x86/fpu: Track AVX usage of tasks
would be more informative and precise. The mechanism
Aubrey,
On Thu, 8 Nov 2018, Aubrey Li wrote:
> Subject: x86/fpu: detect AVX task
What is an AVX task? I know what you mean, but for the casual reader this
is not very informative. So something like:
x86/fpu: Track AVX usage of tasks
would be more informative and precise. The mechanism
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