From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [PATCH] credit: track residual from divisions done during accounting Date: Mon, 25 Feb 2013 11:45:56 +0100 Message-ID: <1361789156.16489.1.camel@Solace> References: <51222E8302000078000BF1F3@nat28.tlf.novell.com> <1361554003.16232.33.camel@Solace> <512B3CF702000078000C0AC6@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============7210795123279206784==" Return-path: In-Reply-To: <512B3CF702000078000C0AC6@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: George Dunlap , xen-devel List-Id: xen-devel@lists.xenproject.org --===============7210795123279206784== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-6rTH155Yb8VqVvhupINV" --=-6rTH155Yb8VqVvhupINV Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2013-02-25 at 09:29 +0000, Jan Beulich wrote: > >>> On 22.02.13 at 18:26, Dario Faggioli wrot= e: > > On Mon, 2013-02-18 at 12:37 +0000, Jan Beulich wrote: > >> --- a/xen/common/sched_credit.c > >> +++ b/xen/common/sched_credit.c > >> > >> @@ -242,6 +244,7 @@ __runq_remove(struct csched_vcpu *svc) > >> static void burn_credits(struct csched_vcpu *svc, s_time_t now) > >> { > >> s_time_t delta; > >> + uint64_t val; > >> unsigned int credits; > >> =20 > >> /* Assert svc is current */ > >> @@ -250,7 +253,10 @@ static void burn_credits(struct csched_v > >> if ( (delta =3D now - svc->start_time) <=3D 0 ) > >> return; > >> =20 > >> - credits =3D (delta*CSCHED_CREDITS_PER_MSEC + MILLISECS(1)/2) / MI= LLISECS(1); > >> + val =3D delta * CSCHED_CREDITS_PER_MSEC + svc->residual; > >> + svc->residual =3D do_div(val, MILLISECS(1)); > >> + credits =3D val; > >> + ASSERT(credits =3D=3D val); > >=20 > > I may be missing something, but how can the assert ever be false, given > > the assignment right before it? >=20 > val being wider than credit, this checks that there was no truncation. >=20 Ok. At least I was right in the "missing something" part. :-) TBH, I figured it had to be something related to that, but was failing to spot it... Sorry for the noise and thanks for the explanation! Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-6rTH155Yb8VqVvhupINV 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 v1.4.12 (GNU/Linux) iEYEABECAAYFAlErQOUACgkQk4XaBE3IOsQg1QCgo4VG2s896fL/UKviXxVanCkE sFQAmgLMs9/kszQxEl5oPSv6Y6auubJp =dBzC -----END PGP SIGNATURE----- --=-6rTH155Yb8VqVvhupINV-- --===============7210795123279206784== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel --===============7210795123279206784==--