From: Andrea Arcangeli <aarcange@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Peter Xu <peterx@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 14/17] KVM: monolithic: x86: inline more exit handlers in vmx.c
Date: Mon, 23 Sep 2019 21:55:27 -0400 [thread overview]
Message-ID: <20190924015527.GC4658@redhat.com> (raw)
In-Reply-To: <a75d04e1-cfd6-fa2e-6120-1f3956e14153@redhat.com>
On Tue, Sep 24, 2019 at 03:25:34AM +0200, Paolo Bonzini wrote:
> On 24/09/19 03:00, Andrea Arcangeli wrote:
> > Before and after this specific commit there is a difference with gcc 8.3.
> >
> > full patchset applied
> >
> > 753699 87971 9616 851286 cfd56 build/arch/x86/kvm/kvm-intel.ko
> >
> > git revert
> >
> > 753739 87971 9616 851326 cfd7e build/arch/x86/kvm/kvm-intel.ko
> >
> > git reset --hard HEAD^
> >
> > 753699 87971 9616 851286 cfd56 build/arch/x86/kvm/kvm-intel.ko
> >
> > git revert
> >
> > 753739 87971 9616 851326 cfd7e build/arch/x86/kvm/kvm-intel.ko
>
> So it's forty bytes. I think we can leave this out.
This commit I reverted adds literally 3 inlines called by 3 functions,
in a very fast path, how many bytes of .text difference did you expect
by dropping some call/ret from a very fast path when you asked me to
test it? I mean it's just a couple of insn each.
I thought the question was if gcc was already inlining without the
hint or not or if it actually grew in size in case I got it wrong and
there were many callers and it was better off not inline, so now I
don't get what was the point of this test if with the result that
confirms it's needed, the patch should be dropped.
It's possible that this patch may not be relevant anymore with the
rename in place of the vmx/svm functions, but if this patch is to be
dropped with the optimal result, then I recommend you to go ahead and
submit a patch to drop __always_inline from the whole kernel because
if it's not good to use it here in a extreme fast path like
handle_external_interrupt and handle_halt, then I don't know what
__always_inline is good for anywhere else in the kernel.
Thanks,
Andrea
next prev parent reply other threads:[~2019-09-24 1:55 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-20 21:24 [PATCH 00/17] KVM monolithic v1 Andrea Arcangeli
2019-09-20 21:24 ` [PATCH 01/17] x86: spec_ctrl: fix SPEC_CTRL initialization after kexec Andrea Arcangeli
2019-09-23 10:22 ` Paolo Bonzini
2019-09-23 15:30 ` Sean Christopherson
2019-09-23 17:34 ` Andrea Arcangeli
2019-09-23 22:27 ` Sean Christopherson
2019-09-20 21:24 ` [PATCH 02/17] KVM: monolithic: x86: convert the kvm_x86_ops methods to external functions Andrea Arcangeli
2019-09-23 10:19 ` Paolo Bonzini
2019-09-23 16:13 ` Sean Christopherson
2019-09-23 16:51 ` Paolo Bonzini
2019-09-23 19:21 ` Andrea Arcangeli
2019-09-20 21:24 ` [PATCH 03/17] KVM: monolithic: x86: handle the request_immediate_exit variation Andrea Arcangeli
2019-09-23 22:35 ` Sean Christopherson
2019-09-23 23:06 ` Andrea Arcangeli
2019-09-23 23:45 ` Sean Christopherson
2019-09-24 0:24 ` Andrea Arcangeli
2019-09-20 21:24 ` [PATCH 04/17] KVM: monolithic: x86: convert the kvm_pmu_ops methods to external functions Andrea Arcangeli
2019-09-20 21:24 ` [PATCH 05/17] KVM: monolithic: x86: enable the kvm_x86_ops " Andrea Arcangeli
2019-09-20 21:24 ` [PATCH 06/17] KVM: monolithic: x86: enable the kvm_pmu_ops " Andrea Arcangeli
2019-09-20 21:24 ` [PATCH 07/17] KVM: monolithic: x86: adjust the section prefixes Andrea Arcangeli
2019-09-23 10:15 ` Paolo Bonzini
2019-09-25 12:13 ` Andrea Arcangeli
2019-09-25 12:32 ` Paolo Bonzini
2019-09-20 21:25 ` [PATCH 08/17] KVM: monolithic: adjust the section prefixes in the KVM common code Andrea Arcangeli
2019-09-20 21:25 ` [PATCH 09/17] KVM: monolithic: x86: remove kvm.ko Andrea Arcangeli
2019-09-20 21:25 ` [PATCH 10/17] KVM: monolithic: x86: use the external functions instead of kvm_x86_ops Andrea Arcangeli
2019-09-23 10:02 ` Paolo Bonzini
2019-09-20 21:25 ` [PATCH 11/17] KVM: monolithic: x86: remove exports Andrea Arcangeli
2019-09-20 21:25 ` [PATCH 12/17] KVM: monolithic: remove exports from KVM common code Andrea Arcangeli
2019-09-20 21:25 ` [PATCH 13/17] KVM: monolithic: x86: drop the kvm_pmu_ops structure Andrea Arcangeli
2019-09-23 10:21 ` Paolo Bonzini
2019-09-24 0:51 ` Andrea Arcangeli
2019-09-24 1:24 ` Paolo Bonzini
2019-09-20 21:25 ` [PATCH 14/17] KVM: monolithic: x86: inline more exit handlers in vmx.c Andrea Arcangeli
2019-09-23 10:19 ` Paolo Bonzini
2019-09-24 1:00 ` Andrea Arcangeli
2019-09-24 1:25 ` Paolo Bonzini
2019-09-24 1:55 ` Andrea Arcangeli [this message]
2019-09-24 2:56 ` Andrea Arcangeli
2019-09-25 7:52 ` Paolo Bonzini
2019-09-20 21:25 ` [PATCH 15/17] KVM: retpolines: x86: eliminate retpoline from vmx.c exit handlers Andrea Arcangeli
2019-09-23 9:31 ` Vitaly Kuznetsov
2019-09-23 9:57 ` Paolo Bonzini
2019-09-23 19:05 ` Andrea Arcangeli
2019-09-23 20:23 ` Sean Christopherson
2019-09-23 21:08 ` Andrea Arcangeli
2019-09-23 21:24 ` Sean Christopherson
2019-09-23 23:43 ` Andrea Arcangeli
2019-09-23 23:52 ` Sean Christopherson
2019-09-24 0:16 ` Paolo Bonzini
2019-09-24 0:35 ` Sean Christopherson
2019-09-24 0:37 ` Paolo Bonzini
2019-09-24 0:15 ` Paolo Bonzini
2019-09-24 0:38 ` Andrea Arcangeli
2019-09-24 0:46 ` Sean Christopherson
2019-09-24 21:46 ` Andrea Arcangeli
2019-09-25 7:50 ` Paolo Bonzini
2019-09-23 16:37 ` Sean Christopherson
2019-09-23 16:53 ` Paolo Bonzini
2019-09-23 17:42 ` Andrea Arcangeli
2019-09-23 18:15 ` Sean Christopherson
2019-09-23 19:12 ` Andrea Arcangeli
[not found] ` <E8FE7592-69C3-455E-8D80-A2D73BB2E14C@dinechin.org>
2019-09-25 20:51 ` Andrea Arcangeli
2019-09-23 16:28 ` Sean Christopherson
2019-09-20 21:25 ` [PATCH 16/17] KVM: retpolines: x86: eliminate retpoline from svm.c " Andrea Arcangeli
2019-09-23 10:01 ` Paolo Bonzini
2019-09-20 21:25 ` [PATCH 17/17] x86: retpolines: eliminate retpoline from msr event handlers Andrea Arcangeli
2019-09-23 15:39 ` [PATCH 00/17] KVM monolithic v1 Sean Christopherson
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