Ping: ILP32 on aarch64 patches

[Ramana Radhakrishnan]

>
>> `4. More testing (LTP, trinity, performance regressions etc.)
>
> Performance, LTP, trinity and glibc testsuites are ran, and
> some regressions found comparing to lp64, but nothing critical
> there. For example, LTP shows ~5 extra fails, and most of them
> are due to weird fail of mkfs tool, which is called in that
> tests. Trinity is OK to me, and performance in lp64 is looking
> the same - some tests little faster, some little slower, all in
> 5% range.


I don't grok enough about LTP to know if those extra failures are
acceptable and will leave that to Catalin and other kernel folks to
comment.

This statement about performance variations with +/- 5% in lp64 is a
bit too much of hand-wavium for me and begs a few questions :) Most
teams fight to get performance improvements across the toolchain for
aarch64, thus dropping overall performance is something in some
situations worries me.

- I'm not familiar with the trinity benchmark. For posterity in this
mailing list archive - can you post a link to it and do you have / can
you post the analysis for this swing in performance ? I'm surprised
that this has an impact on performance on lp64 and if so what
circumstances do you see this performance loss and for what type of
workloads ?  Is trinity a synthetic benchmark which typically has
noise in it that this swing of +/-5% is acceptable ?
- what's the impact on standard lp64 benchmarks? Are we going to see a
loss in performance for benchmarks like SPECCPU - I don't see why
there should be any performance degradation -  but if so can you
explain why ?



regards
Ramana