From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [Question] PARSEC benchmark has smaller execution time in VM than in native? Date: Tue, 1 Mar 2016 23:12:43 +0100 Message-ID: <1456870363.2959.227.camel@citrix.com> References: <20160229160603.GD28725@char.us.oracle.com> <20160229175924.GA26032@char.us.oracle.com> <20160301182017.GA9344@elena.ufimtseva> <20160301203925.GB9344@elena.ufimtseva> <1328562453.20160301225130@eikelenboom.it> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============6657977831963413555==" Return-path: In-Reply-To: <1328562453.20160301225130@eikelenboom.it> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: Sander Eikelenboom , Elena Ufimtseva Cc: Meng Xu , Hyon-Young Choi , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org --===============6657977831963413555== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-8wiW4AcvEOTN2gf/Ojnq" --=-8wiW4AcvEOTN2gf/Ojnq Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2016-03-01 at 22:51 +0100, Sander Eikelenboom wrote: > Tuesday, March 1, 2016, 9:39:25 PM, you wrote: >=20 > > On Tue, Mar 01, 2016 at 02:52:14PM -0500, Meng Xu wrote: > > >=C2=A0 > > > > I dont think I have exhausted all the options here, but it > > > > looked like > > > > two last changes did improve performance, but was still not > > > > comparable to > > > > HVM case. > > > > I am trying to find where regression had happened. Performance > > > > on newer > > > > kernel (I tried 4.5.0-rc4+) was close or better than HVM. > > Just a perhaps silly thought .. but could there be something in the=C2=A0 > time-measuring that could differ and explain the slightly surprising > results ? > I was about to say the exact same thing. In fact, when I can, I always try to measure time either from the host, or even from outside, rather than inside the VM itself. The host should be fine, although that, in Xen, means measuring in Dom0, which thing may be affected by virtualization as well so, from this point of view, outside would be preferrable. However, measuring from outside (and not even from the host, in certain case) is not always possible and/or comes with a price. So, it really depends on the benchmark and on the use case, and in a bunch of them measuring from the guest is actually fine and/or is what one wants. However, do at least consider that as an option for the issue being reported. Thanks and Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-8wiW4AcvEOTN2gf/Ojnq Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEABECAAYFAlbWE9sACgkQk4XaBE3IOsT10gCfSAaBtBXfg7Y8KrraFqMnysFl IjMAn0iLyIjDi3RbAcJT5hKM9DYAEc+Z =6avK -----END PGP SIGNATURE----- --=-8wiW4AcvEOTN2gf/Ojnq-- --===============6657977831963413555== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVuLm9yZwpodHRwOi8vbGlzdHMueGVuLm9y Zy94ZW4tZGV2ZWwK --===============6657977831963413555==--