linux-kernel - Re: [PATCH v6 02/12] x86/paravirt: switch time pvops functions to use static

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Message-ID: <20210310141347.GF23521@zn.tnic>
Date:   Wed, 10 Mar 2021 15:13:47 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Jürgen Groß <jgross@...e.com>
Cc:     xen-devel@...ts.xenproject.org, x86@...nel.org,
        virtualization@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-hyperv@...r.kernel.org, kvm@...r.kernel.org,
        Deep Shah <sdeep@...are.com>,
        "VMware, Inc." <pv-drivers@...are.com>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v6 02/12] x86/paravirt: switch time pvops functions to
 use static_call()

On Wed, Mar 10, 2021 at 08:51:22AM +0100, Jürgen Groß wrote:
> It is combining the two needed actions: update the static call and
> set the paravirt_using_native_sched_clock boolean.

I actually meant what the point of using_native_sched_clock() is but put
this comment at the wrong place, sorry.

> Just had another idea: I could add a function to static_call.h for
> querying the current function. This would avoid the double book keeping
> and could probably be used later when switching other pv_ops calls to
> static_call, too (e.g. pv_is_native_spin_unlock()).
> 
> What do you think?

Yap, that makes sense. Alternatively, you could even add a bitfield to
pv_ops which carries that info and since pv_ops is global...

But yeah, the less bookkeeping the better.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette