similar to: LLVM AutoFDO status

I am looking for advice on a problem observed with -fprofile-sample-use for samples built with the AutoFDO tool I took the "hmmer" benchmark out of SPEC2006 It is initially compiled clnag++ -o hmmer -O3 -std=gnu89 -DSPEC_CPU -DNDEBUG -fno-strict-aliasing -w -g *.c This baseline binary runs in about 164.2 seconds as reported by "perf stat" We build a sample file from this

Hi, all Recently I'm trying to use LLVM PGO and autoFDO. However I have some problems in the process. LLVM source code is updated on April 9th. Operating system is SUSE x86_64 1. Problems in instrumentation based PGO: clang -O2 -fprofile-instr-generate test.c -o a.out ./a.out (then default.profraw is generated) clang -O2 -fprofile-instr-use=default.profraw test.c -o a.out

Hi All, Our team at Facebook is building a new context-sensitive Sample PGO as an alternative to the existing AutoFDO. We’d like to share our motivation, propose a new design, and reveal preliminary results on benchmarks. We will refer to the proposed design as CSSPGO in this RFC. The new CSSPGO leverages simultaneous LBR and stack sampling to construct a full context-sensitive profile. It

On Fri, Aug 12, 2016 at 12:15 PM, Xinliang David Li via llvm-dev < llvm-dev at lists.llvm.org> wrote: > +dehao. > > There are two potential problems: > > 1) the branch gets eliminated in the binary that is being profiled, so > there is no profile data > This seems like a fundamental problem for PGO. Maybe it is also responsible for this bug:

Thanks for the thoughtful questions, David. See my answers inline. Thanks, Wenlei From: Xinliang David Li <davidxl at google.com> Date: Friday, August 7, 2020 at 1:24 PM To: Wenlei He <wenlei at fb.com> Cc: "llvm-dev at lists.llvm.org" <llvm-dev at lists.llvm.org>, Wei Mi <wmi at google.com>, Hongtao Yu <hoy at fb.com> Subject: Re: [RFC] Context-sensitive

On Fri, Aug 7, 2020 at 11:28 PM Hongtao Yu <hoy at fb.com> wrote: > A few add-ons. > > > > *From: *Wenlei He <wenlei at fb.com> > *Date: *Friday, August 7, 2020 at 10:34 PM > *To: *Xinliang David Li <davidxl at google.com> > *Cc: *"llvm-dev at lists.llvm.org" <llvm-dev at lists.llvm.org>, Wei Mi < > wmi at

Also see my replies inline. From: Hongtao Yu <hoy at fb.com> Date: Saturday, August 8, 2020 at 11:25 AM To: Xinliang David Li <davidxl at google.com> Cc: Wenlei He <wenlei at fb.com>, "llvm-dev at lists.llvm.org" <llvm-dev at lists.llvm.org>, Wei Mi <wmi at google.com> Subject: Re: [RFC] Context-sensitive Sample PGO with Pseudo-Instrumentation Replied

Hello! (+cc Adam Nemet, since he presented on optimization remarks at LLVM Dev Mtg 2016) I have a large C++ program, which I am compiling using a sampling profile generated via perf and AutoFDO. I'd like to use this profile in order to show the hotness of each code path that is displayed in the new optimization remarks viewer tool ( https://www.youtube.com/watch?v=qq0q1hfzidg). It seems,

See my answers inline. From: Xinliang David Li <davidxl at google.com> Date: Friday, August 7, 2020 at 7:57 PM To: Wenlei He <wenlei at fb.com> Cc: "llvm-dev at lists.llvm.org" <llvm-dev at lists.llvm.org>, Wei Mi <wmi at google.com>, Hongtao Yu <hoy at fb.com> Subject: Re: [RFC] Context-sensitive Sample PGO with Pseudo-Instrumentation On Fri, Aug 7,

Hi Rahman, Thanks for sharing the BB-info section proposal which is a shiny idea. I think the BB-info and pseudo probes deal with a similar problem in different spaces, i.e., mapping hardware samples to corresponding basic blocks. In the context of pseudo probes, we much focus on mapping samples back to source-level blocks which is the input to the optimizer. Therefore we are building a

> > After the basic profile-based transformations are working, I would like to > add new sources of profile. Mainly, I am thinking of implementing Auto > FDO. > For those who are not familiar with what autoFDO is -- Auto FDO is originally called Sample Based FDO. Its main author is Dehao Chen @google, and Robert Hundt is the one of the main pushers of technology in Google. The

In addition to an IR block id or probe Id, we’ll also need to know the inline context of a probe if it comes from an inlinee. The current pseudo probe encoding is based on a DFS walk of the inline tree. A MIR BB may contain probes from different inlinees, and we may need to extend the BB-info format for encode the inline contexts there. I’m happy to work with you on a encoding format that can be

A few weeks ago, I announced the availability of a conversion tool that converts Linux Perf sample profiles to LLVM's sample profiler ( https://github.com/google/autofdo). I have now ported this tool to the LLVM tree, so it can be made available as part of LLVM. I've got a working version, but I still need to massage the code to use LLVM's own libraries (logging, flags, etc) and adapt

On Apr 23, 2014, at 7:31 AM, Kostya Serebryany <kcc at google.com> wrote: > I've run one proprietary benchmark that reflects a large portion of the google's server side code. > -fprofile-instr-generate leads to 14x slowdown due to counter contention. That's serious. > Admittedly, there is a single hot function that accounts for half of that slowdown, > but even if

On Apr 24, 2014, at 1:33 AM, Dmitry Vyukov <dvyukov at google.com> wrote: >> >> I can see that the behavior of our current instrumentation is going to be a >> problem for the kinds of applications that you’re looking at. If you can >> find a way to get the overhead down without losing accuracy > > What are your requirements for accuracy? > Current

I have started looking at the state of PGO (Profile Guided Optimization) in LLVM.**I want to discuss my high-level plan and make sure I'm not missing anything interesting out. I appreciate any feedback on this, pointers to existing work, patches and anything related to PGO in LLVM. I will be keeping changes to this plan in this web document

Hi all, Here I include an RFC for control flow sensitive AutoFDO (FS-AFDO). This is a joint work with David Li. Questions and feedback are welcome. Thanks, Rong ============= [RFC] Control Flow Sensitive AutoFDO (FS-AFDO) 1. Motivation AFDO profile is derived from PMU samples from running an earlier build binary. PMU samples are indexed by the IP addresses. An offline tool uses the debug

On 2013-06-12 17:23 , Diego Novillo wrote: > > I have started looking at the state of PGO (Profile Guided > Optimization) in LLVM.**I want to discuss my high-level plan and make > sure I'm not missing anything interesting out. I appreciate any > feedback on this, pointers to existing work, patches and anything > related to PGO in LLVM. Good grief. A whole lot of fail

----- Original Message ----- > From: "Andrea Di Biagio" <andrea.dibiagio at gmail.com> > To: "Paul Robinson" <paul.robinson at sony.com> > Cc: "Hal Finkel" <hfinkel at anl.gov>, "David Blaikie" > <dblaikie at gmail.com>, llvm-dev at lists.llvm.org > Sent: Thursday, December 15, 2016 9:05:00 AM > Subject: Re:

Hi Rong, This is a very interesting proposal. We've also observed profile quality degradation from CFG destructive pass like loop rotate, and I can see how this proposal would help improve quality of profile that drives later optimization passes in the pipeline. I have a few questions. * How does this affect today's AutoFDO? Specifically, can users upgrade compiler with FS-AutoFDO