linux-kernel - Re: Performance Regression in Linux Kernel 5.19

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 9 Sep 2022 15:18:40 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Manikandan Jagatheesan <mjagatheesan@...are.com>
Cc:     "bp@...e.de" <bp@...e.de>,
        "jpoimboe@...nel.org" <jpoimboe@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "srivatsa@...il.mit.edu" <srivatsa@...il.mit.edu>,
        Peter Jonasson <pjonasson@...are.com>,
        Yiu Cho Lau <lauyiuch@...are.com>,
        Rajender M <manir@...are.com>,
        Abdul Anshad Azeez <aazees@...are.com>,
        Kodeswaran Kumarasamy <kkumarasamy@...are.com>,
        Rahul Gopakumar <gopakumarr@...are.com>
Subject: Re: Performance Regression in Linux Kernel 5.19

On Fri, Sep 09, 2022 at 11:46:08AM +0000, Manikandan Jagatheesan wrote:
> As part of VMware's performance regression testing for Linux
> Kernel upstream releases, we have evaluated the performance
> of Linux kernel 5.19 against the 5.18 release and we have 
> noticed performance regressions in Linux VMs on ESXi as shown 
> below.
> - Compute(up to -70%)
> - Networking(up to -30%)
> - Storage(up to -13%) 
>  
> After performing the bisect between kernel 5.18 and 5.19, we 
> identified the root cause to be the enablement of IBRS mitigation 
> for spectre_v2 vulnerability by commit 6ad0ad2bf8a6 ("x86/bugs: 
> Report Intel retbleed vulnerability").
>  
> To confirm this, we have disabled the above security mitigation
> through kernel boot parameter(spectre_v2=off) in 5.19 and re-ran
> our tests & confirmed that the performance was on-par with 
> 5.18 release. 

Well, duh.. :-)