ACK/cmnt: [SRU][Zesty][powerpc][PATCH 0/4] Fixes for LP:1709220

Stefan Bader stefan.bader at canonical.com
Mon Aug 21 10:09:26 UTC 2017


On 18.08.2017 17:37, Joseph Salisbury wrote:
> BugLink: http://bugs.launchpad.net/bugs/1709220
> 
> == SRU Justification ==
> These four commits are Radix performance patches specific to powerpc.  
> 
> The patches are reported to help anywhere from 40% up to 3.5X on unixbench fork/exec testcases.
> 
> The first patch was included in mainlne as of 4.12-rc1.  The last three patches are
> still in linux-next.
> 
> == Fixes ==
> commit a5998fcb92552a18713b6aa5c146aa400e4d75ee
> Author: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
> Date:   Wed Apr 26 21:38:17 2017 +1000
> 
>     powerpc/mm/radix: Optimise tlbiel flush all case
> 
> linux-next commit 5ce5fe14ed0302315061cf97ce67accd1b25b938
> Author: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> Date:   Wed Jul 19 14:49:04 2017 +1000
> 
>     powerpc/mm/radix: Improve _tlbiel_pid to be usable for PWC flushes
> 
> linux-next commit a46cc7a90fd8d95bfbb2b27080efe872a1a51db4
> Author: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> Date:   Wed Jul 19 14:49:05 2017 +1000
> 
>     powerpc/mm/radix: Improve TLB/PWC flushes
> 
> linux-next commit 424de9c6e3f89399fc11afc1f53f89c5329132da
> Author: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> Date:   Wed Jul 19 14:49:06 2017 +1000
> 
>     powerpc/mm/radix: Avoid flushing the PWC on every flush_tlb_range
> 
> 
> 
> == Regression Potential ==
> Low since changes are specific to powerpc.
> 
> == Test Case ==
> A test kernel was built with these patches and tested by the original bug reporter.
> 
> Aneesh Kumar K.V (1):
>   powerpc/mm/radix: Optimise tlbiel flush all case
> 
> Benjamin Herrenschmidt (3):
>   powerpc/mm/radix: Improve _tlbiel_pid to be usable for PWC flushes
>   powerpc/mm/radix: Improve TLB/PWC flushes
>   powerpc/mm/radix: Avoid flushing the PWC on every flush_tlb_range
> 
>  .../powerpc/include/asm/book3s/64/tlbflush-radix.h |   5 +-
>  arch/powerpc/mm/pgtable-radix.c                    |   5 +-
>  arch/powerpc/mm/tlb-radix.c                        | 124 +++++++++++++--------
>  3 files changed, 85 insertions(+), 49 deletions(-)
> 
Acked-by: Stefan Bader <stefan.bader at canonical.com>

First nitpicks: the SRU justification should be in the bug reports description
section. I saw someone set verification-done-zesty there. This cannot be true
with the patch set just being reviewed. Maybe some people on the other side need
some update on how this works.

Generally, this is bugging me generally and this set just triggered that bad
feeling again, I think that we allow too much changes into Zesty which are not
stable material. And Zesty is released for a while now. New features should be
the rare exception. Those are for the development release (Artful).
And even if we have to get things into Zesty for some reasons, that should at
least be done in Artful first and stabilize there before becoming SRUs. Also,
personally, I would avoid linux-next material in a SRU as much as possible.

I realize that we picked up a lot of these things previously, so I do not want
to suddenly NACK this one. But I might consider doing so in near future.

-Stefan

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