From: Wanpeng Li <kernellwp@gmail.com>
To: linmiaohe <linmiaohe@huawei.com>
Cc: "hpa@zytor.com" <hpa@zytor.com>,
Paolo Bonzini <pbonzini@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"rkrcmar@redhat.com" <rkrcmar@redhat.com>,
"sean.j.christopherson@intel.com"
<sean.j.christopherson@intel.com>,
"vkuznets@redhat.com" <vkuznets@redhat.com>,
"jmattson@google.com" <jmattson@google.com>,
"joro@8bytes.org" <joro@8bytes.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>
Subject: Re: [PATCH] KVM: x86: small optimization for is_mtrr_mask calculation
Date: Fri, 6 Mar 2020 10:27:26 +0800 [thread overview]
Message-ID: <CANRm+CwRPDpvN_gcO=VbuukjEL2=OPYnxtqoJO6vTk4Z3nudvQ@mail.gmail.com> (raw)
In-Reply-To: <4e9d847ea5d54e4fa83f3bb910242e16@huawei.com>
On Fri, 6 Mar 2020 at 10:23, linmiaohe <linmiaohe@huawei.com> wrote:
>
> hpa@zytor.com wrote:
> >>On March 5, 2020 6:05:40 PM PST, linmiaohe <linmiaohe@huawei.com> wrote:
> >>Hi,
> >>Paolo Bonzini <pbonzini@redhat.com> wrote:
> >>Many thanks for suggestion. What do you mean is like this ?
> >>
> >> index = (msr - 0x200) >> 1;
> >> is_mtrr_mask = msr & 1;
> >>
> >>Thanks again.
> >
> >You realize that the compiler will probably produce exactly the same code, right? As such, it is about making the code easy for the human reader.
> >
> >Even if it didn't, this code is as far from performance critical as one can possibly get.
>
> Yep, it looks gain little. Thanks.
Please post the performance number when you mention optimize XXX later.
Wanpeng
next prev parent reply other threads:[~2020-03-06 2:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-06 2:22 [PATCH] KVM: x86: small optimization for is_mtrr_mask calculation linmiaohe
2020-03-06 2:27 ` Wanpeng Li [this message]
-- strict thread matches above, loose matches on Subject: below --
2020-03-06 2:30 linmiaohe
2020-03-06 2:05 linmiaohe
2020-03-06 2:09 ` hpa
2020-03-05 2:48 linmiaohe
2020-03-05 14:35 ` Paolo Bonzini
2020-03-05 15:10 ` David Laight
2020-03-05 15:25 ` Paolo Bonzini
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CANRm+CwRPDpvN_gcO=VbuukjEL2=OPYnxtqoJO6vTk4Z3nudvQ@mail.gmail.com' \
--to=kernellwp@gmail.com \
--cc=bp@alien8.de \
--cc=hpa@zytor.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linmiaohe@huawei.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=pbonzini@redhat.com \
--cc=rkrcmar@redhat.com \
--cc=sean.j.christopherson@intel.com \
--cc=tglx@linutronix.de \
--cc=vkuznets@redhat.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).