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Thu, 10 Sep 2020 19:32:02 +0000 (UTC) Received: from [10.10.115.84] (ovpn-115-84.rdu2.redhat.com [10.10.115.84]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4EAC85D9F3; Thu, 10 Sep 2020 19:31:59 +0000 (UTC) Subject: Re: [RFC][Patch v1 3/3] PCI: Limit pci_alloc_irq_vectors as per housekeeping CPUs To: Marcelo Tosatti Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-pci@vger.kernel.org, frederic@kernel.org, sassmann@redhat.com, jeffrey.t.kirsher@intel.com, jacob.e.keller@intel.com, jlelli@redhat.com, hch@infradead.org, bhelgaas@google.com, mike.marciniszyn@intel.com, dennis.dalessandro@intel.com, thomas.lendacky@amd.com, jerinj@marvell.com, mathias.nyman@intel.com, jiri@nvidia.com References: <20200909150818.313699-1-nitesh@redhat.com> <20200909150818.313699-4-nitesh@redhat.com> <20200910192208.GA24845@fuller.cnet> From: Nitesh Narayan Lal Autocrypt: addr=nitesh@redhat.com; prefer-encrypt=mutual; keydata= mQINBFl4pQoBEADT/nXR2JOfsCjDgYmE2qonSGjkM1g8S6p9UWD+bf7YEAYYYzZsLtbilFTe z4nL4AV6VJmC7dBIlTi3Mj2eymD/2dkKP6UXlliWkq67feVg1KG+4UIp89lFW7v5Y8Muw3Fm uQbFvxyhN8n3tmhRe+ScWsndSBDxYOZgkbCSIfNPdZrHcnOLfA7xMJZeRCjqUpwhIjxQdFA7 n0s0KZ2cHIsemtBM8b2WXSQG9CjqAJHVkDhrBWKThDRF7k80oiJdEQlTEiVhaEDURXq+2XmG jpCnvRQDb28EJSsQlNEAzwzHMeplddfB0vCg9fRk/kOBMDBtGsTvNT9OYUZD+7jaf0gvBvBB lbKmmMMX7uJB+ejY7bnw6ePNrVPErWyfHzR5WYrIFUtgoR3LigKnw5apzc7UIV9G8uiIcZEn C+QJCK43jgnkPcSmwVPztcrkbC84g1K5v2Dxh9amXKLBA1/i+CAY8JWMTepsFohIFMXNLj+B RJoOcR4HGYXZ6CAJa3Glu3mCmYqHTOKwezJTAvmsCLd3W7WxOGF8BbBjVaPjcZfavOvkin0u DaFvhAmrzN6lL0msY17JCZo046z8oAqkyvEflFbC0S1R/POzehKrzQ1RFRD3/YzzlhmIowkM BpTqNBeHEzQAlIhQuyu1ugmQtfsYYq6FPmWMRfFPes/4JUU/PQARAQABtCVOaXRlc2ggTmFy YXlhbiBMYWwgPG5pbGFsQHJlZGhhdC5jb20+iQI9BBMBCAAnBQJZeKUKAhsjBQkJZgGABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheAAAoJEKOGQNwGMqM56lEP/A2KMs/pu0URcVk/kqVwcBhU SnvB8DP3lDWDnmVrAkFEOnPX7GTbactQ41wF/xwjwmEmTzLrMRZpkqz2y9mV0hWHjqoXbOCS 6RwK3ri5e2ThIPoGxFLt6TrMHgCRwm8YuOSJ97o+uohCTN8pmQ86KMUrDNwMqRkeTRW9wWIQ EdDqW44VwelnyPwcmWHBNNb1Kd8j3xKlHtnS45vc6WuoKxYRBTQOwI/5uFpDZtZ1a5kq9Ak/ MOPDDZpd84rqd+IvgMw5z4a5QlkvOTpScD21G3gjmtTEtyfahltyDK/5i8IaQC3YiXJCrqxE r7/4JMZeOYiKpE9iZMtS90t4wBgbVTqAGH1nE/ifZVAUcCtycD0f3egX9CHe45Ad4fsF3edQ ESa5tZAogiA4Hc/yQpnnf43a3aQ67XPOJXxS0Qptzu4vfF9h7kTKYWSrVesOU3QKYbjEAf95 NewF9FhAlYqYrwIwnuAZ8TdXVDYt7Z3z506//sf6zoRwYIDA8RDqFGRuPMXUsoUnf/KKPrtR ceLcSUP/JCNiYbf1/QtW8S6Ca/4qJFXQHp0knqJPGmwuFHsarSdpvZQ9qpxD3FnuPyo64S2N Dfq8TAeifNp2pAmPY2PAHQ3nOmKgMG8Gn5QiORvMUGzSz8Lo31LW58NdBKbh6bci5+t/HE0H pnyVf5xhNC/FuQINBFl4pQoBEACr+MgxWHUP76oNNYjRiNDhaIVtnPRqxiZ9v4H5FPxJy9UD Bqr54rifr1E+K+yYNPt/Po43vVL2cAyfyI/LVLlhiY4yH6T1n+Di/hSkkviCaf13gczuvgz4 KVYLwojU8+naJUsiCJw01MjO3pg9GQ+47HgsnRjCdNmmHiUQqksMIfd8k3reO9SUNlEmDDNB XuSzkHjE5y/R/6p8uXaVpiKPfHoULjNRWaFc3d2JGmxJpBdpYnajoz61m7XJlgwl/B5Ql/6B dHGaX3VHxOZsfRfugwYF9CkrPbyO5PK7yJ5vaiWre7aQ9bmCtXAomvF1q3/qRwZp77k6i9R3 tWfXjZDOQokw0u6d6DYJ0Vkfcwheg2i/Mf/epQl7Pf846G3PgSnyVK6cRwerBl5a68w7xqVU 4KgAh0DePjtDcbcXsKRT9D63cfyfrNE+ea4i0SVik6+N4nAj1HbzWHTk2KIxTsJXypibOKFX 2VykltxutR1sUfZBYMkfU4PogE7NjVEU7KtuCOSAkYzIWrZNEQrxYkxHLJsWruhSYNRsqVBy KvY6JAsq/i5yhVd5JKKU8wIOgSwC9P6mXYRgwPyfg15GZpnw+Fpey4bCDkT5fMOaCcS+vSU1 UaFmC4Ogzpe2BW2DOaPU5Ik99zUFNn6cRmOOXArrryjFlLT5oSOe4IposgWzdwARAQABiQIl BBgBCAAPBQJZeKUKAhsMBQkJZgGAAAoJEKOGQNwGMqM5ELoP/jj9d9gF1Al4+9bngUlYohYu 0sxyZo9IZ7Yb7cHuJzOMqfgoP4tydP4QCuyd9Q2OHHL5AL4VFNb8SvqAxxYSPuDJTI3JZwI7 d8JTPKwpulMSUaJE8ZH9n8A/+sdC3CAD4QafVBcCcbFe1jifHmQRdDrvHV9Es14QVAOTZhnJ vweENyHEIxkpLsyUUDuVypIo6y/Cws+EBCWt27BJi9GH/EOTB0wb+2ghCs/i3h8a+bi+bS7L FCCm/AxIqxRurh2UySn0P/2+2eZvneJ1/uTgfxnjeSlwQJ1BWzMAdAHQO1/lnbyZgEZEtUZJ x9d9ASekTtJjBMKJXAw7GbB2dAA/QmbA+Q+Xuamzm/1imigz6L6sOt2n/X/SSc33w8RJUyor SvAIoG/zU2Y76pKTgbpQqMDmkmNYFMLcAukpvC4ki3Sf086TdMgkjqtnpTkEElMSFJC8npXv 3QnGGOIfFug/qs8z03DLPBz9VYS26jiiN7QIJVpeeEdN/LKnaz5LO+h5kNAyj44qdF2T2AiF HxnZnxO5JNP5uISQH3FjxxGxJkdJ8jKzZV7aT37sC+Rp0o3KNc+GXTR+GSVq87Xfuhx0LRST NK9ZhT0+qkiN7npFLtNtbzwqaqceq3XhafmCiw8xrtzCnlB/C4SiBr/93Ip4kihXJ0EuHSLn VujM7c/b4pps Organization: Red Hat Inc, Message-ID: Date: Thu, 10 Sep 2020 15:31:57 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200910192208.GA24845@fuller.cnet> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=nitesh@redhat.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Nn7UuK1yQjSSr1T9L7Zv8zociIvpUvuk0" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --Nn7UuK1yQjSSr1T9L7Zv8zociIvpUvuk0 Content-Type: multipart/mixed; boundary="ZCBAnGu3RVN93jfDVzyjk8jPhXft6veOQ" --ZCBAnGu3RVN93jfDVzyjk8jPhXft6veOQ Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Language: en-US On 9/10/20 3:22 PM, Marcelo Tosatti wrote: > On Wed, Sep 09, 2020 at 11:08:18AM -0400, Nitesh Narayan Lal wrote: >> This patch limits the pci_alloc_irq_vectors max vectors that is passed o= n >> by the caller based on the available housekeeping CPUs by only using the >> minimum of the two. >> >> A minimum of the max_vecs passed and available housekeeping CPUs is >> derived to ensure that we don't create excess vectors which can be >> problematic specifically in an RT environment. This is because for an RT >> environment unwanted IRQs are moved to the housekeeping CPUs from >> isolated CPUs to keep the latency overhead to a minimum. If the number o= f >> housekeeping CPUs are significantly lower than that of the isolated CPUs >> we can run into failures while moving these IRQs to housekeeping due to >> per CPU vector limit. >> >> Signed-off-by: Nitesh Narayan Lal >> --- >> include/linux/pci.h | 16 ++++++++++++++++ >> 1 file changed, 16 insertions(+) >> >> diff --git a/include/linux/pci.h b/include/linux/pci.h >> index 835530605c0d..750ba927d963 100644 >> --- a/include/linux/pci.h >> +++ b/include/linux/pci.h >> @@ -38,6 +38,7 @@ >> #include >> #include >> #include >> +#include >> #include >> =20 >> #include >> @@ -1797,6 +1798,21 @@ static inline int >> pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs, >> =09=09 unsigned int max_vecs, unsigned int flags) >> { >> +=09unsigned int num_housekeeping =3D num_housekeeping_cpus(); >> +=09unsigned int num_online =3D num_online_cpus(); >> + >> +=09/* >> +=09 * Try to be conservative and at max only ask for the same number of >> +=09 * vectors as there are housekeeping CPUs. However, skip any >> +=09 * modification to the of max vectors in two conditions: >> +=09 * 1. If the min_vecs requested are higher than that of the >> +=09 * housekeeping CPUs as we don't want to prevent the initializati= on >> +=09 * of a device. >> +=09 * 2. If there are no isolated CPUs as in this case the driver shoul= d >> +=09 * already have taken online CPUs into consideration. >> +=09 */ >> +=09if (min_vecs < num_housekeeping && num_housekeeping !=3D num_online) >> +=09=09max_vecs =3D min_t(int, max_vecs, num_housekeeping); >> =09return pci_alloc_irq_vectors_affinity(dev, min_vecs, max_vecs, flags= , >> =09=09=09=09=09 NULL); >> } > If min_vecs > num_housekeeping, for example: > > /* PCI MSI/MSIx support */ > #define XGBE_MSI_BASE_COUNT 4 > #define XGBE_MSI_MIN_COUNT (XGBE_MSI_BASE_COUNT + 1) > > Then the protection fails. Right, I was ignoring that case. > > How about reducing max_vecs down to min_vecs, if min_vecs > > num_housekeeping ? Yes, I think this makes sense. I will wait a bit to see if anyone else has any other comment and will post the next version then. > --=20 Nitesh --ZCBAnGu3RVN93jfDVzyjk8jPhXft6veOQ-- --Nn7UuK1yQjSSr1T9L7Zv8zociIvpUvuk0 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEkXcoRVGaqvbHPuAGo4ZA3AYyozkFAl9afy0ACgkQo4ZA3AYy oznj9BAArL9Lf/r9SlX2R5OaGs0NE/EhttYtOxiYlsFeXOilO9r2R6nGJLhzEAuz /kmYx2xbVqKyYhJE5qNOO365aiATxu6ZNZixN90++dwGrtj4IjA0Wqdy71IAiW8/ G4jB1UqF2WxA2KWGjaSrIGYfIYXW3J0AukTBxrXcRpEjEp3v5RHBJJwJou7lfEG8 ReQrw57XiS01TzqImv4Ki1g+cD2Iw7Y06b8tes2R9eyZNXwb7AdzZNlw3U0aB+lJ q1ufx5Uya6Q5sVTDxrZ4emeCfFl3g8bQrdV1jXrGudVtR/CuzLtmvzQIAw/RNZiw y8uuQHd8KBFy0m7Diwt/gR671t4Wu3I8p+zcdVqsS29k2hTmFxZCLSgG8SCzpH2u 1dyl3ZrM5Sj/nGJNFkUzNQDxyhVgjOD9I71utncTlXkv9oYbN8GtslviGLje4Hej lLoLsQ/tBMJrmi5VZMVGGMlMRMoyIaMb9f8/7axUxgqu/2IMp34+LABSgiNArTjS w9PdZNS2XlesqzQ2xTLhwPY1lDAQisIaXxFoZwjNr60a9zbwJdU8Hn/ChlhPe899 HPJs2UrKiNazPSafQcxaTuy5gZSmhoICx6CtxKJPz2hDS8ZV+itz2lB18sivia3g 7YCQe7IYYZbup61jJj7M6EbhXHhUbGxnPshRGSYpmHbti5h0pzY= =RA8s -----END PGP SIGNATURE----- --Nn7UuK1yQjSSr1T9L7Zv8zociIvpUvuk0--