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Re: Ping: ILP32 on aarch64 patches
- From: Ramana Radhakrishnan <ramana dot gcc at googlemail dot com>
- To: Yury Norov <ynorov at caviumnetworks dot com>
- Cc: Szabolcs Nagy <nsz at port70 dot net>, Steve Ellcey <sellcey at caviumnetworks dot com>, libc-alpha <libc-alpha at sourceware dot org>, "Carlos O'Donell" <carlos at redhat dot com>, Catalin Marinas <catalin dot marinas at arm dot com>, Maxim Kuvyrkov <maxim dot kuvyrkov at linaro dot org>, Andrew Pinski <pinskia at gmail dot com>, Arnd Bergman <arnd at arndb dot de>, Bamvor Zhangjian <bamvor dot zhangjian at huawei dot com>, Marcus Shawcroft <Marcus dot Shawcroft at arm dot com>
- Date: Fri, 27 Jan 2017 17:39:10 +0000
- Subject: Re: Ping: ILP32 on aarch64 patches
- Authentication-results: sourceware.org; auth=none
- References: <1482949070.2445.4.camel@caviumnetworks.com> <20161228220753.GC6695@port70.net> <20170101222006.GA9513@yury-N73SV>
>
>> `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