From: Thomas Gleixner <tglx@linutronix.de> To: Marcelo Tosatti <mtosatti@redhat.com>, Nitesh Narayan Lal <nitesh@redhat.com> Cc: Jacob Keller <jacob.e.keller@intel.com>, Peter Zijlstra <peterz@infradead.org>, helgaas@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-pci@vger.kernel.org, intel-wired-lan@lists.osuosl.org, frederic@kernel.org, sassmann@redhat.com, jesse.brandeburg@intel.com, lihong.yang@intel.com, jeffrey.t.kirsher@intel.com, jlelli@redhat.com, hch@infradead.org, bhelgaas@google.com, mike.marciniszyn@intel.com, dennis.dalessandro@intel.com, thomas.lendacky@amd.com, jiri@nvidia.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, lgoncalv@redhat.com, Jakub Kicinski <kuba@kernel.org> Subject: Re: [PATCH v4 4/4] PCI: Limit pci_alloc_irq_vectors() to housekeeping CPUs Date: Tue, 27 Oct 2020 15:43:56 +0100 [thread overview] Message-ID: <87k0vb20gj.fsf@nanos.tec.linutronix.de> (raw) In-Reply-To: <20201027114739.GA11336@fuller.cnet> On Tue, Oct 27 2020 at 08:47, Marcelo Tosatti wrote: > On Mon, Oct 26, 2020 at 06:22:29PM -0400, Nitesh Narayan Lal wrote: > However, if per-CPU interrupts are not disabled, then the (for example) > network device is free to include the CPU in its list of destinations. > Which would require one to say, configure RPS (or whatever mechanism > is distributing interrupts). And why is that a problem? If that's possible then you can prevent getting RX interrupts already today. > Hum, it would feel safer (rather than trust the #1 rule to be valid > in all cases) to ask the driver to disable the interrupt (after shutting > down queue) for that particular CPU. > > BTW, Thomas, software is free to configure a particular MSI-X interrupt > to point to any CPU: > > 10.11 MESSAGE SIGNALLED INTERRUPTS I know how MSI works :) > So taking the example where computation happens while isolated and later > stored via block interface, aren't we restricting the usage scenarios > by enforcing the "per-CPU queue has interrupt pointing to owner CPU" > rule? No. For block this is the ideal configuration (think locality) and it prevents vector exhaustion. If you make these interrupts freely routable then you bring back the vector exhaustion problem right away. Now we already established that networking has different requirements, so you have to come up with a different solution for it which allows to work for all use cases. Thanks, tglx
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Gleixner <tglx@linutronix.de> To: intel-wired-lan@osuosl.org Subject: [Intel-wired-lan] [PATCH v4 4/4] PCI: Limit pci_alloc_irq_vectors() to housekeeping CPUs Date: Tue, 27 Oct 2020 15:43:56 +0100 [thread overview] Message-ID: <87k0vb20gj.fsf@nanos.tec.linutronix.de> (raw) In-Reply-To: <20201027114739.GA11336@fuller.cnet> On Tue, Oct 27 2020 at 08:47, Marcelo Tosatti wrote: > On Mon, Oct 26, 2020 at 06:22:29PM -0400, Nitesh Narayan Lal wrote: > However, if per-CPU interrupts are not disabled, then the (for example) > network device is free to include the CPU in its list of destinations. > Which would require one to say, configure RPS (or whatever mechanism > is distributing interrupts). And why is that a problem? If that's possible then you can prevent getting RX interrupts already today. > Hum, it would feel safer (rather than trust the #1 rule to be valid > in all cases) to ask the driver to disable the interrupt (after shutting > down queue) for that particular CPU. > > BTW, Thomas, software is free to configure a particular MSI-X interrupt > to point to any CPU: > > 10.11 MESSAGE SIGNALLED INTERRUPTS I know how MSI works :) > So taking the example where computation happens while isolated and later > stored via block interface, aren't we restricting the usage scenarios > by enforcing the "per-CPU queue has interrupt pointing to owner CPU" > rule? No. For block this is the ideal configuration (think locality) and it prevents vector exhaustion. If you make these interrupts freely routable then you bring back the vector exhaustion problem right away. Now we already established that networking has different requirements, so you have to come up with a different solution for it which allows to work for all use cases. Thanks, tglx
next prev parent reply other threads:[~2020-10-27 15:00 UTC|newest] Thread overview: 110+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-09-28 18:35 [PATCH v4 0/4] isolation: limit msix vectors to housekeeping CPUs Nitesh Narayan Lal 2020-09-28 18:35 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-09-28 18:35 ` [PATCH v4 1/4] sched/isolation: API to get number of " Nitesh Narayan Lal 2020-09-28 18:35 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-09-28 18:35 ` [PATCH v4 2/4] sched/isolation: Extend nohz_full to isolate managed IRQs Nitesh Narayan Lal 2020-09-28 18:35 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-10-23 13:25 ` Peter Zijlstra 2020-10-23 13:25 ` [Intel-wired-lan] " Peter Zijlstra 2020-10-23 13:29 ` Frederic Weisbecker 2020-10-23 13:29 ` [Intel-wired-lan] " Frederic Weisbecker 2020-10-23 13:57 ` Nitesh Narayan Lal 2020-10-23 13:57 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-10-23 13:45 ` Nitesh Narayan Lal 2020-10-23 13:45 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-09-28 18:35 ` [PATCH v4 3/4] i40e: Limit msix vectors to housekeeping CPUs Nitesh Narayan Lal 2020-09-28 18:35 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-09-28 18:35 ` [PATCH v4 4/4] PCI: Limit pci_alloc_irq_vectors() " Nitesh Narayan Lal 2020-09-28 18:35 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-09-28 21:59 ` Bjorn Helgaas 2020-09-28 21:59 ` [Intel-wired-lan] " Bjorn Helgaas 2020-09-29 17:46 ` Christoph Hellwig 2020-09-29 17:46 ` [Intel-wired-lan] " Christoph Hellwig 2020-10-16 12:20 ` Peter Zijlstra 2020-10-16 12:20 ` [Intel-wired-lan] " Peter Zijlstra 2020-10-18 18:14 ` Nitesh Narayan Lal 2020-10-18 18:14 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-10-19 11:11 ` Peter Zijlstra 2020-10-19 11:11 ` [Intel-wired-lan] " Peter Zijlstra 2020-10-19 14:00 ` Marcelo Tosatti 2020-10-19 14:00 ` [Intel-wired-lan] " Marcelo Tosatti 2020-10-19 14:25 ` Nitesh Narayan Lal 2020-10-19 14:25 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-10-20 7:30 ` Peter Zijlstra 2020-10-20 7:30 ` [Intel-wired-lan] " Peter Zijlstra 2020-10-20 13:00 ` Nitesh Narayan Lal 2020-10-20 13:00 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-10-20 13:41 ` Peter Zijlstra 2020-10-20 13:41 ` [Intel-wired-lan] " Peter Zijlstra 2020-10-20 14:39 ` Nitesh Narayan Lal 2020-10-20 14:39 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-10-22 17:47 ` Nitesh Narayan Lal 2020-10-22 17:47 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-10-23 8:58 ` Peter Zijlstra 2020-10-23 8:58 ` [Intel-wired-lan] " Peter Zijlstra 2020-10-23 13:10 ` Nitesh Narayan Lal 2020-10-23 13:10 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-10-23 21:00 ` Thomas Gleixner 2020-10-23 21:00 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-26 13:35 ` Nitesh Narayan Lal 2020-10-26 13:35 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-10-26 13:57 ` Thomas Gleixner 2020-10-26 13:57 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-26 17:30 ` Marcelo Tosatti 2020-10-26 17:30 ` [Intel-wired-lan] " Marcelo Tosatti 2020-10-26 19:00 ` Thomas Gleixner 2020-10-26 19:00 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-26 19:11 ` Marcelo Tosatti 2020-10-26 19:11 ` [Intel-wired-lan] " Marcelo Tosatti 2020-10-26 19:21 ` Jacob Keller 2020-10-26 19:21 ` [Intel-wired-lan] " Jacob Keller 2020-10-26 20:11 ` Thomas Gleixner 2020-10-26 20:11 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-26 21:11 ` Jacob Keller 2020-10-26 21:11 ` [Intel-wired-lan] " Jacob Keller 2020-10-26 21:50 ` Thomas Gleixner 2020-10-26 21:50 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-26 22:13 ` Jakub Kicinski 2020-10-26 22:13 ` [Intel-wired-lan] " Jakub Kicinski 2020-10-26 22:46 ` Thomas Gleixner 2020-10-26 22:46 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-26 22:52 ` Jacob Keller 2020-10-26 22:52 ` [Intel-wired-lan] " Jacob Keller 2020-10-26 22:22 ` Nitesh Narayan Lal 2020-10-26 22:22 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-10-26 22:49 ` Thomas Gleixner 2020-10-26 22:49 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-26 23:08 ` Jacob Keller 2020-10-26 23:08 ` [Intel-wired-lan] " Jacob Keller 2020-10-27 14:28 ` Thomas Gleixner 2020-10-27 14:28 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-27 11:47 ` Marcelo Tosatti 2020-10-27 11:47 ` [Intel-wired-lan] " Marcelo Tosatti 2020-10-27 14:43 ` Thomas Gleixner [this message] 2020-10-27 14:43 ` Thomas Gleixner 2020-10-19 14:21 ` Frederic Weisbecker 2020-10-19 14:21 ` [Intel-wired-lan] " Frederic Weisbecker 2020-10-20 14:16 ` Thomas Gleixner 2020-10-20 14:16 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-20 16:18 ` Nitesh Narayan Lal 2020-10-20 16:18 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-10-20 18:07 ` Thomas Gleixner 2020-10-20 18:07 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-21 20:25 ` Thomas Gleixner 2020-10-21 20:25 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-21 21:04 ` Nitesh Narayan Lal 2020-10-21 21:04 ` [Intel-wired-lan] " Nitesh Narayan Lal 2020-10-22 0:02 ` Jakub Kicinski 2020-10-22 0:02 ` [Intel-wired-lan] " Jakub Kicinski 2020-10-22 0:27 ` Jacob Keller 2020-10-22 0:27 ` [Intel-wired-lan] " Jacob Keller 2020-10-22 8:28 ` Thomas Gleixner 2020-10-22 8:28 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-22 12:28 ` Marcelo Tosatti 2020-10-22 12:28 ` [Intel-wired-lan] " Marcelo Tosatti 2020-10-22 22:39 ` Thomas Gleixner 2020-10-22 22:39 ` [Intel-wired-lan] " Thomas Gleixner 2020-10-01 15:49 ` [PATCH v4 0/4] isolation: limit msix vectors " Frederic Weisbecker 2020-10-01 15:49 ` [Intel-wired-lan] " Frederic Weisbecker 2020-10-08 21:40 ` Nitesh Narayan Lal 2020-10-08 21:40 ` [Intel-wired-lan] " Nitesh Narayan Lal
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=87k0vb20gj.fsf@nanos.tec.linutronix.de \ --to=tglx@linutronix.de \ --cc=bhelgaas@google.com \ --cc=dennis.dalessandro@intel.com \ --cc=frederic@kernel.org \ --cc=hch@infradead.org \ --cc=helgaas@kernel.org \ --cc=intel-wired-lan@lists.osuosl.org \ --cc=jacob.e.keller@intel.com \ --cc=jeffrey.t.kirsher@intel.com \ --cc=jesse.brandeburg@intel.com \ --cc=jiri@nvidia.com \ --cc=jlelli@redhat.com \ --cc=juri.lelli@redhat.com \ --cc=kuba@kernel.org \ --cc=lgoncalv@redhat.com \ --cc=lihong.yang@intel.com \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-pci@vger.kernel.org \ --cc=mike.marciniszyn@intel.com \ --cc=mingo@redhat.com \ --cc=mtosatti@redhat.com \ --cc=netdev@vger.kernel.org \ --cc=nitesh@redhat.com \ --cc=peterz@infradead.org \ --cc=sassmann@redhat.com \ --cc=thomas.lendacky@amd.com \ --cc=vincent.guittot@linaro.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.