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Fri, 8 Nov 2019 15:42:57 +0000 (UTC) Received: from [10.36.117.0] (unknown [10.36.117.0]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5B2475D6BB; Fri, 8 Nov 2019 15:42:55 +0000 (UTC) Subject: Re: [PULL 06/28] spapr: Set VSMT to smp_threads by default From: Laurent Vivier To: David Gibson References: <20191024081813.2115-1-david@gibson.dropbear.id.au> <20191024081813.2115-7-david@gibson.dropbear.id.au> <9aebac7e-8ea3-0c16-30ca-251bcddd7699@redhat.com> <20191108142610.GM2461@umbus.Home> Autocrypt: addr=lvivier@redhat.com; prefer-encrypt=mutual; keydata= mQINBFYFJhkBEAC2me7w2+RizYOKZM+vZCx69GTewOwqzHrrHSG07MUAxJ6AY29/+HYf6EY2 WoeuLWDmXE7A3oJoIsRecD6BXHTb0OYS20lS608anr3B0xn5g0BX7es9Mw+hV/pL+63EOCVm SUVTEQwbGQN62guOKnJJJfphbbv82glIC/Ei4Ky8BwZkUuXd7d5NFJKC9/GDrbWdj75cDNQx UZ9XXbXEKY9MHX83Uy7JFoiFDMOVHn55HnncflUncO0zDzY7CxFeQFwYRbsCXOUL9yBtqLer Ky8/yjBskIlNrp0uQSt9LMoMsdSjYLYhvk1StsNPg74+s4u0Q6z45+l8RAsgLw5OLtTa+ePM JyS7OIGNYxAX6eZk1+91a6tnqfyPcMbduxyBaYXn94HUG162BeuyBkbNoIDkB7pCByed1A7q q9/FbuTDwgVGVLYthYSfTtN0Y60OgNkWCMtFwKxRaXt1WFA5ceqinN/XkgA+vf2Ch72zBkJL RBIhfOPFv5f2Hkkj0MvsUXpOWaOjatiu0fpPo6Hw14UEpywke1zN4NKubApQOlNKZZC4hu6/ 8pv2t4HRi7s0K88jQYBRPObjrN5+owtI51xMaYzvPitHQ2053LmgsOdN9EKOqZeHAYG2SmRW LOxYWKX14YkZI5j/TXfKlTpwSMvXho+efN4kgFvFmP6WT+tPnwARAQABtCNMYXVyZW50IFZp dmllciA8bHZpdmllckByZWRoYXQuY29tPokCOAQTAQIAIgUCVgVQgAIbAwYLCQgHAwIGFQgC CQoLBBYCAwECHgECF4AACgkQ8ww4vT8vvjwpgg//fSGy0Rs/t8cPFuzoY1cex4limJQfReLr SJXCANg9NOWy/bFK5wunj+h/RCFxIFhZcyXveurkBwYikDPUrBoBRoOJY/BHK0iZo7/WQkur 6H5losVZtrotmKOGnP/lJYZ3H6OWvXzdz8LL5hb3TvGOP68K8Bn8UsIaZJoeiKhaNR0sOJyI YYbgFQPWMHfVwHD/U+/gqRhD7apVysxv5by/pKDln1I5v0cRRH6hd8M8oXgKhF2+rAOL7gvh jEHSSWKUlMjC7YwwjSZmUkL+TQyE18e2XBk85X8Da3FznrLiHZFHQ/NzETYxRjnOzD7/kOVy gKD/o7asyWQVU65mh/ECrtjfhtCBSYmIIVkopoLaVJ/kEbVJQegT2P6NgERC/31kmTF69vn8 uQyW11Hk8tyubicByL3/XVBrq4jZdJW3cePNJbTNaT0d/bjMg5zCWHbMErUib2Nellnbg6bc 2HLDe0NLVPuRZhHUHM9hO/JNnHfvgiRQDh6loNOUnm9Iw2YiVgZNnT4soUehMZ7au8PwSl4I KYE4ulJ8RRiydN7fES3IZWmOPlyskp1QMQBD/w16o+lEtY6HSFEzsK3o0vuBRBVp2WKnssVH qeeV01ZHw0bvWKjxVNOksP98eJfWLfV9l9e7s6TaAeySKRRubtJ+21PRuYAxKsaueBfUE7ZT 7ze0LUxhdXJlbnQgVml2aWVyIChSZWQgSGF0KSA8bHZpdmllckByZWRoYXQuY29tPokCOAQT AQIAIgUCVgUmGQIbAwYLCQgHAwIGFQgCCQoLBBYCAwECHgECF4AACgkQ8ww4vT8vvjxtNBAA o2xGmbXl9vJQALkj7MVlsMlgewQ1rdoZl+bZ6ythTSBsqwwtl1BUTQGA1GF2LAchRVYca5bJ lw4ai5OdZ/rc5dco2XgrRFtj1np703BzNEhGU1EFxtms/Y9YOobq/GZpck5rK8jV4osEb8oc 3xEgCm/xFwI/2DOe0/s2cHKzRkvdmKWEDhT1M+7UhtSCnloX776zCsrofYiHP2kasFyMa/5R 9J1Rt9Ax/jEAX5vFJ8+NPf68497nBfrAtLM3Xp03YJSr/LDxer44Mevhz8dFw7IMRLhnuSfr 8jP93lr6Wa8zOe3pGmFXZWpNdkV/L0HaeKwTyDKKdUDH4U7SBnE1gcDfe9x08G+oDfVhqED8 qStKCxPYxRUKIdUjGPF3f5oj7N56Q5zZaZkfxeLNTQ13LDt3wGbVHyZxzFc81B+qT8mkm74y RbeVSuviPTYjbBQ66GsUgiZZpDUyJ6s54fWqQdJf4VFwd7M/mS8WEejbSjglGHMxMGiBeRik Y0+ur5KAF7z0D1KfW1kHO9ImQ0FbEbMbTMf9u2+QOCrSWOz/rj23EwPrCQ2TSRI2fWakMJZ+ zQZvy+ei3D7lZ09I9BT/GfFkTIONgtNfDxwyMc4v4XyP0IvvZs/YZqt7j3atyTZM0S2HSaZ9 rXmQYkBt1/u691cZfvy+Tr2xZaDpFcjPkci5Ag0EVgUmGQEQALxSQRbl/QOnmssVDxWhHM5T Gxl7oLNJms2zmBpcmlrIsn8nNz0rRyxT460k2niaTwowSRK8KWVDeAW6ZAaWiYjLlTunoKwv F8vP3JyWpBz0diTxL5o+xpvy/Q6YU3BNefdq8Vy3rFsxgW7mMSrI/CxJ667y8ot5DVugeS2N yHfmZlPGE0Nsy7hlebS4liisXOrN3jFzasKyUws3VXek4V65lHwB23BVzsnFMn/bw/rPliqX Gcwl8CoJu8dSyrCcd1Ibs0/Inq9S9+t0VmWiQWfQkz4rvEeTQkp/VfgZ6z98JRW7S6l6eoph oWs0/ZyRfOm+QVSqRfFZdxdP2PlGeIFMC3fXJgygXJkFPyWkVElr76JTbtSHsGWbt6xUlYHK XWo+xf9WgtLeby3cfSkEchACrxDrQpj+Jt/JFP+q997dybkyZ5IoHWuPkn7uZGBrKIHmBunT co1+cKSuRiSCYpBIXZMHCzPgVDjk4viPbrV9NwRkmaOxVvye0vctJeWvJ6KA7NoAURplIGCq kCRwg0MmLrfoZnK/gRqVJ/f6adhU1oo6z4p2/z3PemA0C0ANatgHgBb90cd16AUxpdEQmOCm dNnNJF/3Zt3inzF+NFzHoM5Vwq6rc1JPjfC3oqRLJzqAEHBDjQFlqNR3IFCIAo4SYQRBdAHB CzkM4rWyRhuVABEBAAGJAh8EGAECAAkFAlYFJhkCGwwACgkQ8ww4vT8vvjwg9w//VQrcnVg3 TsjEybxDEUBm8dBmnKqcnTBFmxN5FFtIWlEuY8+YMiWRykd8Ln9RJ/98/ghABHz9TN8TRo2b 6WimV64FmlVn17Ri6FgFU3xNt9TTEChqAcNg88eYryKsYpFwegGpwUlaUaaGh1m9OrTzcQy+ klVfZWaVJ9Nw0keoGRGb8j4XjVpL8+2xOhXKrM1fzzb8JtAuSbuzZSQPDwQEI5CKKxp7zf76 J21YeRrEW4WDznPyVcDTa+tz++q2S/BpP4W98bXCBIuQgs2m+OflERv5c3Ojldp04/S4NEjX EYRWdiCxN7ca5iPml5gLtuvhJMSy36glU6IW9kn30IWuSoBpTkgV7rLUEhh9Ms82VWW/h2Tx L8enfx40PrfbDtWwqRID3WY8jLrjKfTdR3LW8BnUDNkG+c4FzvvGUs8AvuqxxyHbXAfDx9o/ jXfPHVRmJVhSmd+hC3mcQ+4iX5bBPBPMoDqSoLt5w9GoQQ6gDVP2ZjTWqwSRMLzNr37rJjZ1 pt0DCMMTbiYIUcrhX8eveCJtY7NGWNyxFCRkhxRuGcpwPmRVDwOl39MB3iTsRighiMnijkbL XiKoJ5CDVvX5yicNqYJPKh5MFXN1bvsBkmYiStMRbrD0HoY1kx5/VozBtc70OU0EB8Wrv9hZ D+Ofp0T3KOr1RUHvCZoLURfFhSQ= Message-ID: <8913aece-ce82-1045-cb70-d55a87d66192@redhat.com> Date: Fri, 8 Nov 2019 16:42:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-MC-Unique: 3i8DK6XDMiOfMXlfl3de9g-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org, Juan Quintela , groug@kaod.org, qemu-devel@nongnu.org, qemu-ppc@nongnu.org, clg@kaod.org, "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 08/11/2019 16:34, Laurent Vivier wrote: > On 08/11/2019 15:26, David Gibson wrote: >> On Fri, Nov 08, 2019 at 02:11:03PM +0100, Laurent Vivier wrote: >>> On 24/10/2019 10:17, David Gibson wrote: >>>> From: Greg Kurz >>>> >>>> Support for setting VSMT is available in KVM since linux-4.13. Most di= stros >>>> that support KVM on POWER already have it. It thus seem reasonable eno= ugh >>>> to have the default machine to set VSMT to smp_threads. >>>> >>>> This brings contiguous VCPU ids and thus brings their upper bound down= to >>>> the machine's max_cpus. This is especially useful for XIVE KVM devices= , >>>> which may thus allocate only one VP descriptor per VCPU. >>>> >>>> Signed-off-by: Greg Kurz >>>> Message-Id: <157010411885.246126.12610015369068227139.stgit@bahia.lan> >>>> Signed-off-by: David Gibson >>>> --- >>>> hw/ppc/spapr.c | 7 ++++++- >>>> include/hw/ppc/spapr.h | 1 + >>>> 2 files changed, 7 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c >>>> index 4eb97d3a9b..428b834f30 100644 >>>> --- a/hw/ppc/spapr.c >>>> +++ b/hw/ppc/spapr.c >>>> @@ -2496,6 +2496,7 @@ static CPUArchId *spapr_find_cpu_slot(MachineSta= te *ms, uint32_t id, int *idx) >>>> static void spapr_set_vsmt_mode(SpaprMachineState *spapr, Error **err= p) >>>> { >>>> MachineState *ms =3D MACHINE(spapr); >>>> + SpaprMachineClass *smc =3D SPAPR_MACHINE_GET_CLASS(spapr); >>>> Error *local_err =3D NULL; >>>> bool vsmt_user =3D !!spapr->vsmt; >>>> int kvm_smt =3D kvmppc_smt_threads(); >>>> @@ -2522,7 +2523,7 @@ static void spapr_set_vsmt_mode(SpaprMachineStat= e *spapr, Error **errp) >>>> goto out; >>>> } >>>> /* In this case, spapr->vsmt has been set by the command line= */ >>>> - } else { >>>> + } else if (!smc->smp_threads_vsmt) { >>>> /* >>>> * Default VSMT value is tricky, because we need it to be as >>>> * consistent as possible (for migration), but this requires >>>> @@ -2531,6 +2532,8 @@ static void spapr_set_vsmt_mode(SpaprMachineStat= e *spapr, Error **errp) >>>> * overwhelmingly common case in production systems. >>>> */ >>>> spapr->vsmt =3D MAX(8, smp_threads); >>>> + } else { >>>> + spapr->vsmt =3D smp_threads; >>>> } >>>> =20 >>>> /* KVM: If necessary, set the SMT mode: */ >>>> @@ -4438,6 +4441,7 @@ static void spapr_machine_class_init(ObjectClass= *oc, void *data) >>>> smc->irq =3D &spapr_irq_dual; >>>> smc->dr_phb_enabled =3D true; >>>> smc->linux_pci_probe =3D true; >>>> + smc->smp_threads_vsmt =3D true; >>>> } >>>> =20 >>>> static const TypeInfo spapr_machine_info =3D { >>>> @@ -4505,6 +4509,7 @@ static void spapr_machine_4_1_class_options(Mach= ineClass *mc) >>>> =20 >>>> spapr_machine_4_2_class_options(mc); >>>> smc->linux_pci_probe =3D false; >>>> + smc->smp_threads_vsmt =3D false; >>>> compat_props_add(mc->compat_props, hw_compat_4_1, hw_compat_4_1_l= en); >>>> compat_props_add(mc->compat_props, compat, G_N_ELEMENTS(compat)); >>>> } >>>> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h >>>> index cbd1a4c9f3..2009eb64f9 100644 >>>> --- a/include/hw/ppc/spapr.h >>>> +++ b/include/hw/ppc/spapr.h >>>> @@ -122,6 +122,7 @@ struct SpaprMachineClass { >>>> bool broken_host_serial_model; /* present real host info to the g= uest */ >>>> bool pre_4_1_migration; /* don't migrate hpt-max-page-size */ >>>> bool linux_pci_probe; >>>> + bool smp_threads_vsmt; /* set VSMT to smp_threads by default */ >>>> =20 >>>> void (*phb_placement)(SpaprMachineState *spapr, uint32_t index, >>>> uint64_t *buid, hwaddr *pio,=20 >>>> >>> >>> This patch breaks tests/migration-test on P8 host with kernel older tha= n >>> 4.3 because it tries by default to set the VSMT to 1. >>> >>> qemu-system-ppc64: Failed to set KVM's VSMT mode to 1 (errno -22) >>> On PPC, a VM with 1 threads/core on a host with 8 threads/core requires >>> the use of VSMT mode 1. >>> This KVM seems to be too old to support VSMT. >>> >>> As this is clearly intentional, is there a way to fix migration-test? >> >> Hrm. I believe the argument for this was that the broken kernels were >> old enough we didn't care. What platform are you testing on where >> you're hitting this? >> >=20 > I'm going to propose a patch to fix this problem. > (it was on RHEL7) Patch sent: [PATCH] spapr: Fix VSMT mode when it is not supported by the kernel Message-Id: <20191108154035.12913-1-lvivier@redhat.com> Thanks, Laurent