[llvm-dev] Enable vectorizer-maximize-bandwidth by default?

[Dehao Chen via llvm-dev]

Thanks for the update. I think overall consensus is supportive for this
change. If no one objects by then end of tomorrow (Tuesday), I will submit
the patch to make vectorizer-maximize-bandwidth on by default.

Thanks,
Dehao

On Mon, Jun 12, 2017 at 3:41 AM, Agabaria, Mohammed <
mohammed.agabaria at intel.com> wrote:

> Guys, Just to clarify that with the current fix in SLM there is no need to
> wait for other issues to be fixed (minor issue).
>
> So you can move on with your patch.
>
>
>
> *From:* Agabaria, Mohammed
> *Sent:* Wednesday, June 07, 2017 15:24
> *To:* Zaks, Ayal <ayal.zaks at intel.com>; Chandler Carruth <
> chandlerc at gmail.com>; Flamedoge <code.kchoi at gmail.com>; Dehao Chen <
> dehao at google.com>
> *Cc:* llvm-dev <llvm-dev at lists.llvm.org>
> *Subject:* RE: [llvm-dev] Enable vectorizer-maximize-bandwidth by default?
>
>
>
> Guys I have uploaded a fix on phabricator which fix the issue in SLM:
> https://reviews.llvm.org/D33983
>
>
>
> *From:* Zaks, Ayal
> *Sent:* Tuesday, June 06, 2017 22:32
> *To:* Chandler Carruth <chandlerc at gmail.com>; Agabaria, Mohammed <
> mohammed.agabaria at intel.com>; Flamedoge <code.kchoi at gmail.com>; Dehao
> Chen <dehao at google.com>
> *Cc:* llvm-dev <llvm-dev at lists.llvm.org>
> *Subject:* RE: [llvm-dev] Enable vectorizer-maximize-bandwidth by default?
>
>
>
> Chandler> Have you considered contributing these benchmarks to the LLVM
> test suite?
>
>
>
> These benchmarks are not ours to contribute; they’re from the EEMBC
> standard, whose availability is similar in nature to that of SPEC.
>
>
>
>
>
> *From:* llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org
> <llvm-dev-bounces at lists.llvm.org>] *On Behalf Of *Chandler Carruth via
> llvm-dev
> *Sent:* Tuesday, May 30, 2017 23:07
> *To:* Agabaria, Mohammed <mohammed.agabaria at intel.com>; Flamedoge <
> code.kchoi at gmail.com>; Dehao Chen <dehao at google.com>
> *Cc:* llvm-dev <llvm-dev at lists.llvm.org>
> *Subject:* Re: [llvm-dev] Enable vectorizer-maximize-bandwidth by default?
>
>
>
> On Tue, May 30, 2017 at 1:40 AM Agabaria, Mohammed via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> We’re seeing nice improvements but also significant degradations on IA,
> which we would like to investigate before the patch is committed.
>
>
>
> Major degradations we see:
>
>
>
> networking
>
>    ip_pktcheckb1m          -6.80 %
>
>    ip_pktcheckb2m          -6.74 %
>
>    ip_pktcheckb4m          -7.57 %
>
>    ip_pktcheckb512k       -6.58 %
>
> Telecom
>
>    autcor00data_1          -78.02 %
>
>    autcor00data_2          -76.80 %
>
>    autcor00data_3          -77.00 %
>
> (on Atom)
>
>
>
> We still working on creating reproducers.
>
> In general we support this patch, just want to have a chance to
> investigate the issues. We need a few days for that.
>
>
>
> I mean, OK... but keep in mind that Dehao's original email went out over a
> week ago, so this patch has already been held up a while. As these
> benchmarks aren't readily available, we also can't do anything to help
> until a test case is posted.
>
>
>
> Have you considered contributing these benchmarks to the LLVM test suite?
>
>
>
>
>
>
>
>
>
> *From:* llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org
> <llvm-dev-bounces at lists.llvm.org>] *On Behalf Of *Chandler Carruth via
> llvm-dev
> *Sent:* Tuesday, May 30, 2017 11:27
> *To:* Flamedoge <code.kchoi at gmail.com>; Dehao Chen <dehao at google.com>
> *Cc:* llvm-dev <llvm-dev at lists.llvm.org>
> *Subject:* Re: [llvm-dev] Enable vectorizer-maximize-bandwidth by default?
>
>
>
> If you care about such hardware, please run benchmarks with the flag?
>
>
>
> Dehao has made this flag available. It is important that those who care
> about particular hardware provid ebenchmark results. Not everyone in the
> community will have access to particular hardware variants.
>
>
>
> On Tue, May 30, 2017 at 1:14 AM Flamedoge <code.kchoi at gmail.com> wrote:
>
> Thank you for running these.
>
>
>
> May I suggest testing on AVX2 capable hardware? That would be Intel
> Haswell, AMD Carrizo and up.
>
> I'm not sure what "vectorizer-maximize-bandwidth" implies, but doubling
> the vector lanes may help light up parallel regions.
>
>
>
> Kevin
>
>
>
> On Tue, May 30, 2017 at 12:58 AM, Chandler Carruth via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> On Fri, May 19, 2017 at 4:01 PM Adam Nemet via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> I will run it on Cyclone/AArch64 next week.
>
>
>
> FYI, we're still waiting on these Adam...
>
>
>
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