From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3xSd6B2jj4zDqrP for ; Thu, 10 Aug 2017 16:10:26 +1000 (AEST) Date: Thu, 10 Aug 2017 15:54:26 +1000 From: David Gibson To: Benjamin Herrenschmidt Cc: =?iso-8859-1?Q?C=E9dric?= Le Goater , linuxppc-dev@lists.ozlabs.org, Michael Ellerman , Paul Mackerras Subject: Re: [PATCH 02/10] powerpc/xive: guest exploitation of the XIVE interrupt controller Message-ID: <20170810055426.GV13670@umbus.fritz.box> References: <1502182579-990-1-git-send-email-clg@kaod.org> <1502182579-990-3-git-send-email-clg@kaod.org> <20170809035306.GC13670@umbus.fritz.box> <20170810042849.GU13670@umbus.fritz.box> <1502340360.2563.53.camel@kernel.crashing.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="X6f5cqjOqKjuoPgI" In-Reply-To: <1502340360.2563.53.camel@kernel.crashing.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --X6f5cqjOqKjuoPgI Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Aug 10, 2017 at 02:46:00PM +1000, Benjamin Herrenschmidt wrote: > On Thu, 2017-08-10 at 14:28 +1000, David Gibson wrote: > >=20 > > Also, will POWER9 always have doorbells? In which case you could > > reduce it to 3 options. >=20 > The problem with doorbells on POWER9 guests is that they may have > to trap and be emulated by the hypervisor, since the guest threads > on P9 don't have to match the HW threads of the core. >=20 > Thus it's quite possible that using XIVE for IPIs is actually faster > than doorbells in that case. Ok, well unless there's a compelling reason to use doorbells you can instead make it 3 cases with POWER9 never using doorbells. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --X6f5cqjOqKjuoPgI Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAlmL9QwACgkQbDjKyiDZ s5LaORAAzqfoo64K3ZYcMtqQ8f13n9CpgqxsCSSc/nxMzhnMB2ynehZzLJtFbypu CIoKUJPJGzES+6lOrv4zj9oiQEwBwBWrI/tEYDx/5UVVeo1AcDvpt3U2z8PfTjB6 ldBXAiQ5MpLX79nsZaFsjK/z8+sNeV+LDGeV7lu8InD1GaDkjnq8Eg/QKbx4KVl7 +eNlQSrWjnYd6Lie4bUJ0bPbSRvIPSRs1f/n/NvmiZ1qgr0DxigKV1UXFgpikDgV zudUYGvWtxey7fO2P8cxjnhF+m3C5xW/woaY5kR8PjjLogzGtfz7URXt/vsFhiuJ UvXBMlDVRAOl7oJPWupNBD0s90BCdcdbVaqpXSQqv6s8elNISiHD2hCqwp2SgD0Q x32qeOALMGceqbBbEEWu+W0QFO0G1n11+ixi9g4Y0hlMwM8jMLnCfU179w6pFBFo heNr8gGxvnB/kpEY+l7XI/tlMqfCAByJ05gS51SshiuhQHKlIZxtKwG6HLDq9dw2 bhQDzaJHM3QKubwZ1trayh95S7ITtQrvDb0d19vhSa8LS7GL+fZPiOBaZJ89ewYJ dZOF6Vsa60DnoTjfto4H9uShzk+j5meQQMfkTr0ZqGazowehLl5Y3fhRh4+1gd7k jzYpGXiJJix/ZBIuP6qvucYSJNFktXSznZG4s9UQ1xhqPCHrWfc= =DLs6 -----END PGP SIGNATURE----- --X6f5cqjOqKjuoPgI--