From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: HVM guest performance regression Date: Fri, 26 May 2017 19:04:14 +0200 Message-ID: <1495818254.7393.73.camel@citrix.com> References: <55443407-5d99-0830-e8e0-6c2044c18ec9@suse.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============9214752391679294281==" Return-path: Received: from mail6.bemta6.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dEIfG-0001xU-Ks for xen-devel@lists.xenproject.org; Fri, 26 May 2017 17:04:38 +0000 In-Reply-To: <55443407-5d99-0830-e8e0-6c2044c18ec9@suse.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: Juergen Gross , xen-devel Cc: Wei Liu , Stefano Stabellini , Ian Jackson List-Id: xen-devel@lists.xenproject.org --===============9214752391679294281== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="=-25MDxiJlbtomjuGXGYOE" --=-25MDxiJlbtomjuGXGYOE Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2017-05-26 at 18:14 +0200, Juergen Gross wrote: > Looking for the reason of a performance regression of HVM guests > under > Xen 4.7 against 4.5 I found the reason to be commit > c26f92b8fce3c9df17f7ef035b54d97cbe931c7a ("libxl: remove > freemem_slack") > in Xen 4.6. >=20 > The problem occurred when dom0 had to be ballooned down when starting > the guest. The performance of some micro benchmarks dropped by about > a factor of 2 with above commit. >=20 Performance of micro benchmarks run _inside_ the guest, I'm guessing? > Interesting point is that the performance of the guest will depend on > the amount of free memory being available at guest creation time. > When there was barely enough memory available for starting the guest > the performance will remain low even if memory is being freed later. >=20 OOC, what kind of host? Big? Small? NUMA, non-NUMA?, etc Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-25MDxiJlbtomjuGXGYOE 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 iQIcBAABCAAGBQJZKGAPAAoJEBZCeImluHPuMcMP/27HHhmfPmPA9NxyBgvn1tmH r6694fn1HqqW52HaDxNXUn8SyjA4w8AYNrhErCa43eM5fId4HjupAeUJ9GHaGKPE k7pAjppnaHWYbOfc7hOjYsJLRhtXadmP0bGRQbQ8tNU4BJrTcYCZr7YDMShQjG06 5fZFnFJP0I5rml5qu6BsLI7qYpkRtJJhlWOtczZfiOEVU4Ftq222WQ9AhEpW6irz 7I2Be7LLEeG85FlI1UjyAn+glhCbUT8gkxUeFMnoWk5lW3OjVzHYHyyX+f2/SdyD oQyr5TG0aXnSD+X6aTKtBB67F55YaJ6HCWvSoBbP1dOCyxP31xnLNu7Yw+6H4CW1 vdXyyfDr5E549CBfall4ZP1sEPKas7YUO0zkEpJl/tOozw9VAXi8b9TPrZgdh6FQ RbEA3BucN6M2JNaX583LZjnVFx8eF0oecKOJfqGVizxvNLJPFWPgzfVecSdErYjb r4DqcslT+ZUFB2S7BQ6v5+UJyON9aljrrAuD2iL6v487KDRsWS5M+3Vj6zrwwJEa Arpq7HsV1y7+9cviXuSvl4Ion7+FvOZsf7k9JXdHf0d7ca9J6Ea0SizzQCkqoy4l aRvojeGJKPqPvfw4jLArWKN1QGMSmcGBk/2x4UHs205oy+hSGih9bfM79XEJV5w8 v/Lv/xO7OUj6DrWKSgQL =wY30 -----END PGP SIGNATURE----- --=-25MDxiJlbtomjuGXGYOE-- --===============9214752391679294281== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVuLm9yZwpodHRwczovL2xpc3RzLnhlbi5v cmcveGVuLWRldmVsCg== --===============9214752391679294281==--