Re: [PATCH v2 0/4] Update memcpy, memset etc. for M7/M8 architectures

[Babu Moger]

David,  Thanks for applying.

On 8/10/2017 4:38 PM, David Miller wrote:

From: Babu Moger 
Date: Mon,  7 Aug 2017 17:52:48 -0600


This series of patches updates the memcpy, memset, copy_to_user,
copy_from_user etc for SPARC M7/M8 architecture.

This doesn't build, you cannot assume the existence of "%ncc", it is a
recent addition.

Furthermore there is no need to ever use %ncc in v9 targetted code
anyways.

I'll fix that up, but this was a really disappointing build failure
to hit.

Thank you..


Meanwhile, two questions:

1) Is this also faster on T4 as well?  If it is, we can just get rid
of the T4 routines and use this on those chips as well.


At the time of this work, our focus was mostly on T7 and T8. We did not 
test this code on T4.
For T4 and other older configs we used NG4 versions. I would think it 
would require some

changes to make it work on T4.


2) There has been a lot of discussion and consideration put into how
a memcpy/memset routine might be really great for the local cpu
but overall pessimize performance for other cpus either locally
on the same core (contention for physical resources such as
ports to the store buffer and/or L3 cache) or on other cores.

Has any such study been done into these issues wrt. this new code?

No, we have not done this kind of study.

Re: [PATCH v2 0/4] Update memcpy, memset etc. for M7/M8 architectures

[Babu Moger]

David,  Thanks for applying.

On 8/10/2017 4:38 PM, David Miller wrote:

From: Babu Moger 
Date: Mon,  7 Aug 2017 17:52:48 -0600


This series of patches updates the memcpy, memset, copy_to_user,
copy_from_user etc for SPARC M7/M8 architecture.

This doesn't build, you cannot assume the existence of "%ncc", it is a
recent addition.

Furthermore there is no need to ever use %ncc in v9 targetted code
anyways.

I'll fix that up, but this was a really disappointing build failure
to hit.

Thank you..


Meanwhile, two questions:

1) Is this also faster on T4 as well?  If it is, we can just get rid
of the T4 routines and use this on those chips as well.


At the time of this work, our focus was mostly on T7 and T8. We did not 
test this code on T4.
For T4 and other older configs we used NG4 versions. I would think it 
would require some

changes to make it work on T4.


2) There has been a lot of discussion and consideration put into how
a memcpy/memset routine might be really great for the local cpu
but overall pessimize performance for other cpus either locally
on the same core (contention for physical resources such as
ports to the store buffer and/or L3 cache) or on other cores.

Has any such study been done into these issues wrt. this new code?

No, we have not done this kind of study.

Re: [PATCH v2 0/4] Update memcpy, memset etc. for M7/M8 architectures

[David Miller]

From: Babu Moger 
Date: Mon,  7 Aug 2017 17:52:48 -0600

> This series of patches updates the memcpy, memset, copy_to_user,
> copy_from_user etc for SPARC M7/M8 architecture.

This doesn't build, you cannot assume the existence of "%ncc", it is a
recent addition.

Furthermore there is no need to ever use %ncc in v9 targetted code
anyways.

I'll fix that up, but this was a really disappointing build failure
to hit.

Meanwhile, two questions:

1) Is this also faster on T4 as well?  If it is, we can just get rid
   of the T4 routines and use this on those chips as well.

2) There has been a lot of discussion and consideration put into how
   a memcpy/memset routine might be really great for the local cpu
   but overall pessimize performance for other cpus either locally
   on the same core (contention for physical resources such as
   ports to the store buffer and/or L3 cache) or on other cores.

   Has any such study been done into these issues wrt. this new code?

Re: [PATCH v2 0/4] Update memcpy, memset etc. for M7/M8 architectures

[David Miller]

From: Babu Moger 
Date: Mon,  7 Aug 2017 17:52:48 -0600

> This series of patches updates the memcpy, memset, copy_to_user,
> copy_from_user etc for SPARC M7/M8 architecture.

This doesn't build, you cannot assume the existence of "%ncc", it is a
recent addition.

Furthermore there is no need to ever use %ncc in v9 targetted code
anyways.

I'll fix that up, but this was a really disappointing build failure
to hit.

Meanwhile, two questions:

1) Is this also faster on T4 as well?  If it is, we can just get rid
   of the T4 routines and use this on those chips as well.

2) There has been a lot of discussion and consideration put into how
   a memcpy/memset routine might be really great for the local cpu
   but overall pessimize performance for other cpus either locally
   on the same core (contention for physical resources such as
   ports to the store buffer and/or L3 cache) or on other cores.

   Has any such study been done into these issues wrt. this new code?