From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: Read Performance issue when Xen Hypervisor is activated Date: Fri, 30 Dec 2016 17:34:58 +0100 Message-ID: <1483115698.32021.102.camel@citrix.com> References: <64f352a7a8a14ec19da5d07374b48eb6@ip-projects.de> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============8855111673561362963==" Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cN093-0007HW-C2 for xen-devel@lists.xenproject.org; Fri, 30 Dec 2016 16:35:05 +0000 In-Reply-To: <64f352a7a8a14ec19da5d07374b48eb6@ip-projects.de> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: Michael Schinzel , Xen-devel Cc: Roger Pau Monne List-Id: xen-devel@lists.xenproject.org --===============8855111673561362963== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="=-IMX7x85ijbwWWK1oamlI" --=-IMX7x85ijbwWWK1oamlI Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable [Cc-ing someone which have done disk benchmark in somewhat recent time] On Tue, 2016-12-27 at 14:26 +0000, Michael Schinzel wrote: > We have searched in the last days more and more for the cause of this > performance issue. > =C2=A0 > In cooperation with the datacenter, we change some hardware to check, > if the problem already proceeds. We put the RAID Controller included > all RAID Arrays to another Supermicro Mainboard: X10SLM-F with only > one CPU. The result was, we got 400 MB/s read Speed. So it seems > there is an issue with the Servers Mainboard / CPU and the Xen > Hypervisor but, we also change the Mainboard to an Supermicro X9DR3-F=20 > with the actual BIOS Version 3.2a =E2=80=93 these also do not solved the > problem with the performance. > =C2=A0 > What we also have done: > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Upgraded Hypervis= or from default Debian 8 =E2=80=93 4.4.1 to 4.8. > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Tested some kerne= l boot configurations\ > I think it would be useful to know more about your configuration, e.g., are these tests being done in Dom0? How many vCPUs and memory does Dom0 have? > With an non hypervisor Kernel, the system also uses the read Cache of > the controller and after some read operations at the same file, it > gets 1.2 G/s back from the Cache. At Xen Hypervisor Kernel, it seems > the system do not use any caching operations. I also tested a bit > with hdparm: > =C2=A0 > root@v7:~# hdparm -Tt /dev/sdb > =C2=A0 > /dev/sdb: > Timing cached reads:=C2=A0=C2=A0 14060 MB in=C2=A0 1.99 seconds =3D 7076.= 16 MB/sec > Timing buffered disk reads: 304 MB in=C2=A0 3.01 seconds =3D 100.85 MB/se= c > =C2=A0 > This Performance is horrable. It is a RAID 10 with read/write cache > and SSD Caching functions. > =C2=A0 > Does somebody know how Xen proceeds with such Caching Systems? > =C2=A0 > =C2=A0 > Yours sincerely > =C2=A0 > Michael Schinzel --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-IMX7x85ijbwWWK1oamlI 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 iQIcBAABCAAGBQJYZoyyAAoJEBZCeImluHPuOkIP/RNj515BSVClsuk2Z3O8howB 2BYouAlhnf51/Admf0lJL6xj+OSBqLj36jLcfjMXEdhD6ryrAYa6cAH78eyilqSZ pBGU0aFFwH0yt4FeCNTFk3j0N1Q4bpL8Tdj/hc/c8iaWnxpMBmtbGPlxJtIGORtc 3eux5Uw8iKOO/aiwvegn0VwUy6gTqZs7jEoJhfu0biAJvCo+d3SNMDA6y8ikzIcF TG0YCIzgkQjKccTcZVYiMJhxaoTYaFA3HdXAgvItlmHtCS3esHdP2RmKooaFIng3 X48l7ySmBpJcgGtov5vAmP82keVgbqadQDTr5daxhjZJzvZdo8K7aijNb+9ECnFe LzPjwVSyIp0eTLv0JKRH6R5u1QhzMqfUbHfKKmISXzQz7zXXRKE4DRBa4v1auiD4 X3yfda2MvHOC8/c6TL12JC+w6L5CVidYzBZecVOE4eOM9ypccC9cBU/TzO8ntlI0 41SuETrNaI0wpdBQ/gB/WcZg/0h/T3H9YZ6Hnu9i3td1XeXpg2Bze0EGCtnQLXT2 H2JafYlcFdA7TKYXqaUwZjYrl8Q63MBOfnjZF71Z8xKcB134xbpaYmWCItdQ65zV lcVqlDdEOEkrzn3BlG2CjPaHNpZFiL9uFRjtEg8zVL1knolnS1jVIh8RobCXZa37 tfBJMZkMP9bZYJfP9KlX =J0B5 -----END PGP SIGNATURE----- --=-IMX7x85ijbwWWK1oamlI-- --===============8855111673561362963== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVuLm9yZwpodHRwczovL2xpc3RzLnhlbi5v cmcveGVuLWRldmVsCg== --===============8855111673561362963==--