linux-kernel - Re: [PATCH 1/1] selftests: KVM: set affinity of VM to right CPUs

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Message-ID: <YVSoQD+yuQzlKLoM@google.com>
Date:   Wed, 29 Sep 2021 17:54:08 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Dongli Zhang <dongli.zhang@...cle.com>
Cc:     kvm@...r.kernel.org, linux-kselftest@...r.kernel.org,
        pbonzini@...hat.com, shuah@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] selftests: KVM: set affinity of VM to right CPUs

On Tue, Sep 28, 2021, Dongli Zhang wrote:
> 
> On 9/27/21 12:22 PM, Sean Christopherson wrote:
> Perhaps a linked list is more suitable to here (when there are 1024 cpus and the
> task is bound to both 1 and 1022) ... to pre-save the possible cpus in a list
> and to only move to next cpu in the list for each iteration.
> 
> However, I think min_cpu/max_cpu is good enough for selttests case.

Yeah, it's annoying that there's no CPU_SET_FOR_EACH so that x86 could optimize
it to use BSF :-/

> Would you please let me know if you would like to send above with my
> Reported-by, or if you would like me to send with your Suggested-by.

If you don't mind, I'll send a patch, I want to fiddle with the migration loop to
see if I can make it less magical/ugly.