From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [PATCH v6 for Xen 4.7 1/4] xen: enable per-VCPU parameter settings for RTDS scheduler Date: Mon, 14 Mar 2016 10:10:23 +0100 Message-ID: <1457946623.3102.636.camel@citrix.com> References: <1457286958-5427-1-git-send-email-lichong659@gmail.com> <1457286958-5427-2-git-send-email-lichong659@gmail.com> <20160308190950.GT31271@citrix.com> <1457539804.3102.425.camel@citrix.com> <56E05F8F02000078000DAF15@prv-mh.provo.novell.com> <56E6866202000078000DBECD@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============4034781872229713356==" Return-path: In-Reply-To: <56E6866202000078000DBECD@prv-mh.provo.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: Jan Beulich , Chong Li Cc: Chong Li , Wei Liu , Sisu Xi , George Dunlap , xen-devel , Meng Xu , Dagaen Golomb List-Id: xen-devel@lists.xenproject.org --===============4034781872229713356== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-8CgqKTTAhke7v+lN942c" --=-8CgqKTTAhke7v+lN942c Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2016-03-14 at 02:37 -0600, Jan Beulich wrote: > >=20 > > >=20 > > > >=20 > > > > On 13.03.16 at 18:05, wrote: > > So I still keep my design here? > >=20 > > Dario, Jan and Wei, > Afaic: >=20 I agree almost on everything too. About this: > > 3) Use printk(XENLOG_G_WARNING ...) here, because of its rate limit > > feature. > I'd say XENLOG_G_DEBUG, and even that only if you really think > the message is useful. >=20 I think it has some value to have this in the logs. In fact, someone that ended up with small values --either by bug/chance, or in general without a specific need for them-- and is seeing performance/scheduling issues will still be able to find this. And printing it somewhere else than in Xen is impractical (see my reply to Wei). However, we may well print it just once, as soon as the first vcpu with potentially problematic parameters is hit, and then silence it. Linux has things like WARN_ON_ONCE to do this: http://lxr.free-electrons.com/source/include/asm-generic/bug.h#L109 I don't see anything like it in Xen, so you'd need to either implement it, or arrange for something with the same effect locally. If we just print it once, I'd keep it G_WARNING. Thanks and Regards, Dario --=C2=A0 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-8CgqKTTAhke7v+lN942c 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 iEYEABECAAYFAlbmf/8ACgkQk4XaBE3IOsRSFQCfTviXrx00zEgoikTuzgiEu67v FMAAn1Pa2pviPmFaXlJaQpxAjHTAkUNN =Ehbo -----END PGP SIGNATURE----- --=-8CgqKTTAhke7v+lN942c-- --===============4034781872229713356== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVuLm9yZwpodHRwOi8vbGlzdHMueGVuLm9y Zy94ZW4tZGV2ZWwK --===============4034781872229713356==--