linux-kernel - Re: [PATCH v2 4/4] x86/kvm/hyper-v: avoid open-coding stimer_mark_pending() in kvm_hv_notify_acked

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Date:   Tue, 27 Nov 2018 08:49:33 +0000
From:   Roman Kagan <rkagan@...tuozzo.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "Michael Kelley (EOSG)" <Michael.H.Kelley@...rosoft.com>
Subject: Re: [PATCH v2 4/4] x86/kvm/hyper-v: avoid open-coding
 stimer_mark_pending() in kvm_hv_notify_acked_sint()

On Mon, Nov 26, 2018 at 04:47:32PM +0100, Vitaly Kuznetsov wrote:
> stimers_pending optimization only helps us to avoid multiple
> kvm_make_request() calls. This doesn't happen very often and these
> calls are very cheap in the first place, remove open-coded version of
> stimer_mark_pending() from kvm_hv_notify_acked_sint().

Frankly speaking, I've yet to see a guest that configures more than one
SynIC timer.  So it was indeed a bit of overengineering in the first
place.

> Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
>  arch/x86/kvm/hyperv.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)

Reviewed-by: Roman Kagan <rkagan@...tuozzo.com>