From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nikola Ciprich Subject: KVM got slow after adding more physical memory to host Date: Tue, 6 Sep 2011 16:02:01 +0200 Message-ID: <20110906140201.GF18218@pcnci.linuxbox.cz> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="TmwHKJoIRFM7Mu/A" Cc: nikola.ciprich@linuxbox.cz To: kvm@vger.kernel.org Return-path: Received: from gwu.lbox.cz ([62.245.111.132]:59048 "EHLO gwu.lbox.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753795Ab1IFOex (ORCPT ); Tue, 6 Sep 2011 10:34:53 -0400 Received: from linuxbox.linuxbox.cz (linuxbox.linuxbox.cz [10.76.66.10]) by gwu.lbox.cz (Sendmail) with ESMTP id p86E22wA032478 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 6 Sep 2011 16:02:02 +0200 Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: --TmwHKJoIRFM7Mu/A Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello, I'm trying to solve quite a weird problem on one of our customers' box. It's quad core Xeon X3430 @ 2.40GHz, running 64bit centos with 2.6.38 (I a= lso tried upgrading to 2.6.39). After increasing physical memory from 16 to 20GB, all guest got incredibly = slow, starting just one windows or linux guest causes host to be quite slow, and quest seems to= be even slower. hardware virtualisation is on, KVM is used, no relevant update since the up= date. here's about 3 seconds of kvm_stat: kvm_exit 659513 103922 kvm_entry 659505 103920 kvm_emulate_insn 631118 99344 kvm_exit(IO_INSTRUCTION) 625223 98398 kvm_userspace_exit 624979 98359 kvm_pio 624970 98357 but according to atop, there is almost no I/O activity from guests, and run= ning top in them shows them to really be idle... but they eat like 60-70% of host CPU core time each.. Do You have any idea on what should I check? thanks a lot in advance nik --=20 ------------------------------------- Ing. Nikola CIPRICH LinuxBox.cz, s.r.o. 28. rijna 168, 709 01 Ostrava tel.: +420 596 603 142 fax: +420 596 621 273 mobil: +420 777 093 799 www.linuxbox.cz mobil servis: +420 737 238 656 email servis: servis@linuxbox.cz ------------------------------------- --TmwHKJoIRFM7Mu/A Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEARECAAYFAk5mJ9kACgkQ3xdJJrLygV4AswCdHTNdbRPZREPC5/CzoxcBzHTt 4p4AoMzINOe2nvBucDhTh7itKKirZpwc =rzag -----END PGP SIGNATURE----- --TmwHKJoIRFM7Mu/A--