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Date: Mon, 29 Jul 2024 11:53:03 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Rong Xu <xur@google.com>
Cc: Han Shen <shenhan@google.com>, Sriraman Tallam <tmsriram@google.com>,
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Subject: Re: [PATCH 6/6] Add Propeller configuration for kernel build.
Message-ID: <20240729095303.GD37996@noisy.programming.kicks-ass.net>
References: <20240728203001.2551083-1-xur@google.com>
 <20240728203001.2551083-7-xur@google.com>
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In-Reply-To: <20240728203001.2551083-7-xur@google.com>

On Sun, Jul 28, 2024 at 01:29:59PM -0700, Rong Xu wrote:
> Add the build support for using Clang's Propeller optimizer. Like
> AutoFDO, Propeller uses hardware sampling to gather information
> about the frequency of execution of different code paths within a
> binary. This information is then used to guide the compiler's
> optimization decisions, resulting in a more efficient binary.
> 
> The support requires a Clang compiler LLVM 19 or later, and the
> create_llvm_prof tool
> (https://github.com/google/autofdo/releases/tag/v0.30.1). This

What's the relation between this and llvm-profgen? Is the above simply
a google 'internal' proof of concept thing that will eventually make its
way into llvm-profgen?

It seems a bit weird LLVM landed propeller without the required profile
generation tool.