From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH] Reorganise and then fixup the pseries cpu hotplug code From: Michael Ellerman To: jschopp In-Reply-To: <45612D68.8080404@austin.ibm.com> References: <20061116154051.GB2008@localdomain> <20061117033638.0E24B67BCE@ozlabs.org> <20061117180456.GG23600@austin.ibm.com> <1163984914.7832.16.camel@localhost.localdomain> <45612D68.8080404@austin.ibm.com> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-WKoeIF9knjOLdn8+5KJx" Date: Mon, 20 Nov 2006 16:59:15 +1100 Message-Id: <1164002356.13318.4.camel@localhost.localdomain> Mime-Version: 1.0 Cc: srinivasa@in.ibm.com, ego@in.ibm.com, linuxppc-dev@ozlabs.org, paulus@samba.org, Anton Blanchard , ntl@pobox.com Reply-To: michael@ellerman.id.au List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --=-WKoeIF9knjOLdn8+5KJx Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Sun, 2006-11-19 at 22:22 -0600, jschopp wrote: > >>> + /* Isolation and deallocation are definatly done by > >> ^^^^^^^^^ > >> typo >=20 > That word definitely gives me trouble. I'd imagine the typo originated w= ith me. Yeah it's definitely a tricky one ;) > >> > >>> + * drslot_chrp_cpu. If they were not they would be > >>> + * done here. Change isolate state to Isolate and > >>> + * change allocation-state to Unusable. > >>> + */ > >>> + paca[cpu].cpu_start =3D 0; > >> I can't figure out what the comment means with respect=20 > >> to this code ...=20 > >=20 > > Me either. It's unchanged from the original merge of cpu hotplug: > > http://kernel.org/git/?p=3Dlinux/kernel/git/torvalds/old-2.6-bkcvs.git;= a=3Dcommit;h=3D24c13f21f0a6abe07020a959990da2b134e6734f > > http://kernel.org/git/?p=3Dlinux/kernel/git/torvalds/old-2.6-bkcvs.git;= a=3Dblobdiff;h=3D72144b6122f9336e7fa242e50b65b099df0cd72b;hp=3Df671515c0676= e61064ae414273fa4546d0c04938;hb=3D24c13f21f0a6abe07020a959990da2b134e6734f;= f=3Darch/ppc64/kernel/smp.c > >=20 > > Which carries the name of one Joel Schopp :) > >=20 > > Grepping the tree at that point finds no other mention of > > drslot_chrp_cpu, so I think it's a stale comment - we should probably > > just rip it out - Joel? >=20 > It might be clearer by saying "the userspace program drslot_chrp_cpu" or = "isolation and=20 > deallocation occur in userspace, so just stop the cpu. If isolation and = deallocation ever=20 > move from userpace to kernel space they would go here". On pseries dynam= ic partitioning=20 > or cpu guard (the things that initiate a cpu hotplug) all call a userspac= e program drmgr,=20 > which calls drslot_chrp_cpu, which then talks to the firmware to isolate = and unallocate=20 > (on remove, the opposite on add) after it has hotplug removed the cpu via= the /sys=20 > interface. This allows the cpu to be reassigned to another partition. >=20 > At least that's what I remember from back then when we did it. Though I = don't think it's=20 > changed any. Feel free to make the comment more intelligible. OK, it didn't occur to me that it was referring to userspace. I'll change it to: /* * Isolation and deallocation occur in userspace, so just stop the cpu. * If isolation and deallocation ever move from userpace to kernel space * we would do them here. */ Sound OK? cheers --=20 Michael Ellerman OzLabs, IBM Australia Development Lab wwweb: http://michael.ellerman.id.au phone: +61 2 6212 1183 (tie line 70 21183) We do not inherit the earth from our ancestors, we borrow it from our children. - S.M.A.R.T Person --=-WKoeIF9knjOLdn8+5KJx Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (GNU/Linux) iD8DBQBFYUQydSjSd0sB4dIRArovAJ9yNzBo6FNbdNsxfBh6SxFL260nBgCcCtad SexREwSBVXLJhgADL6M9hpA= =KyhT -----END PGP SIGNATURE----- --=-WKoeIF9knjOLdn8+5KJx--