linux-kernel - Re: [PATCH v3 0/3] VMSCAPE optimization for BHI variant

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Message-ID: <f07e3144-edcd-4b5c-8b4a-fb6bdd90943b@intel.com>
Date: Mon, 3 Nov 2025 12:07:30 -0800
From: Dave Hansen <dave.hansen@...el.com>
To: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, x86@...nel.org,
 "H. Peter Anvin" <hpa@...or.com>, Josh Poimboeuf <jpoimboe@...nel.org>,
 David Kaplan <david.kaplan@....com>, Sean Christopherson
 <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
 Asit Mallick <asit.k.mallick@...el.com>, Tao Zhang <tao1.zhang@...el.com>
Subject: Re: [PATCH v3 0/3] VMSCAPE optimization for BHI variant

On 10/27/25 16:43, Pawan Gupta wrote:
> | iPerf user-net | IBPB    | BHB Clear |
> |----------------|---------|-----------|
> | UDP 1-vCPU_p1  | -12.5%  |   1.3%    |
...

Could you clarify what "1.3%" means? Is that relative to the baseline,
or relative to the IBPB number?

If it's relative to the baseline, then this data either looks wrong or
noisy since there are a lot of places where adding the BHB Clear loop
makes things faster.