linux-kernel - Re: [PATCH v6 1/3] x86/fpu: Measure the Latency of XSAVES and XRSTORS

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Message-ID: <ZPj3BpLlGkBeYcW7@gmail.com>
Date:   Thu, 7 Sep 2023 00:02:46 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Yi Sun <yi.sun@...el.com>, Andi Kleen <ak@...ux.intel.com>,
        tglx@...utronix.de, linux-kernel@...r.kernel.org, x86@...nel.org,
        sohil.mehta@...el.com, ilpo.jarvinen@...ux.intel.com,
        heng.su@...el.com, tony.luck@...el.com,
        dave.hansen@...ux.intel.com, yi.sun@...el.intel.com
Subject: Re: [PATCH v6 1/3] x86/fpu: Measure the Latency of XSAVES and XRSTORS


* Dave Hansen <dave.hansen@...el.com> wrote:

> On 9/6/23 02:18, Yi Sun wrote:
> > Or just use PT
> 
> I'd really like to be able to use this mechanism across a wide range of 
> systems over time and vendors.  For instance, if Intel's AVX512 XSAVE 
> implementation is much faster than AMD's, it would be nice to show some 
> apples-to-apples data to motivate AMD to do better.  We can't do that 
> with PT.

Ack - and with the explicit tooling support, it's also very easy to provide 
such numbers.

As long as the regular FPU code paths do not get new tracing overhead 
added, this looks like a useful tool.

Thanks,

	Ingo