Date: Thu, 4 Apr 2013 19:33:34 +0300
From: Gleb Natapov <gleb@redhat.com>
To: Alexander Graf <agraf@suse.de>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
        Marcelo Tosatti <mtosatti@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
        Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
        Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>,
        Alex Williamson <alex.williamson@redhat.com>,
        Will Deacon <will.deacon@arm.com>,
        Christoffer Dall <c.dall@virtualopensystems.com>,
        Sasha Levin <sasha.levin@oracle.com>,
        Andrew Morton <akpm@linux-foundation.org>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org
Subject: Re: [PATCH RFC] kvm: add PV MMIO EVENTFD
Message-ID: <20130404163334.GE27672@redhat.com>
References: <20130404120825.GD17919@redhat.com>
 <959E147D-EB7B-4F4B-9F84-4F1BBA98DEF8@suse.de>
 <20130404123806.GG17919@redhat.com>
 <EF153515-9835-4FB9-B6BC-73D0BDC86492@suse.de>
 <20130404124501.GH17919@redhat.com>
 <1B68D701-103D-4B1A-8F5E-3916753699CB@suse.de>
 <20130404125649.GI17919@redhat.com>
 <8E65D34D-2DA7-4C2E-9C3E-BE3A7DBC3279@suse.de>
 <20130404133318.GI6467@redhat.com>
 <14B443D5-5785-487D-9EA3-0AD20141BC06@suse.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <14B443D5-5785-487D-9EA3-0AD20141BC06@suse.de>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1089
Lines: 37

On Thu, Apr 04, 2013 at 05:36:40PM +0200, Alexander Graf wrote:
> > 
> > #define GOAL (1ull << 30)
> > 
> >        do {
> >                iterations *= 2;
> >                t1 = rdtsc();
> > 
> >                        for (i = 0; i < iterations; ++i)
> >                                func();
> >                t2 = rdtsc();
> >        } while ((t2 - t1) < GOAL);
> >        printf("%s %d\n", test->name, (int)((t2 - t1) / iterations));
> 
> So it's the number of cycles per run.
> 
> That means translated my numbers are:
> 
>   MMIO: 4307
>   PIO: 3658
>   HCALL: 1756
> 
> MMIO - PIO = 649
> 
> which aligns roughly with your PV MMIO callback.
> 
> My MMIO benchmark was to poke the LAPIC version register. That does go through instruction emulation, no?
> 
It should and PIO 'in' or string also goes through the emulator.

--
			Gleb.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/