From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754452AbdDLQAY (ORCPT ); Wed, 12 Apr 2017 12:00:24 -0400 Received: from mail-eopbgr50047.outbound.protection.outlook.com ([40.107.5.47]:64632 "EHLO EUR03-VE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753950AbdDLQAW (ORCPT ); Wed, 12 Apr 2017 12:00:22 -0400 Authentication-Results: mellanox.com; dkim=none (message not signed) header.d=none;mellanox.com; dmarc=none action=none header.from=mellanox.com; Subject: Re: [v2] PCI: Add an option to control probing of VFs before enabling SR-IOV To: Bjorn Helgaas References: <1490198038-20465-1-git-send-email-bodong@mellanox.com> <20170411211211.GB14778@bhelgaas-glaptop.roam.corp.google.com> <2e39e1b6-0205-2780-0223-3552d2c871a3@mellanox.com> <20170412152216.GA25197@bhelgaas-glaptop.roam.corp.google.com> CC: , , , , Eli Cohen From: Bodong Wang Message-ID: <601c08f0-ccc9-984f-0fce-5fc6012fe1f9@mellanox.com> Date: Wed, 12 Apr 2017 11:00:06 -0500 User-Agent: Mozilla/5.0 (Windows NT 6.1; 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This can save host side resource usage by VF >>>> instances which would be eventually probed to VMs. >>>> >>>> Add a new PCI sysfs interface "sriov_probe_vfs" to control that >>> >from the PF, all current callers still retain the same functionality. >>>> To modify it, echo 0/n/N (disable probe) or 1/y/Y (enable probe) to >>>> >>>> /sys/bus/pci/devices//sriov_probe_vfs >>> Is this basically the same functionality as /sys/bus/pci/drivers_autoprobe, >>> but limited to a specific PF? I.e., could we accomplish the same thing >>> with the following? >>> >>> # echo 0 > /sys/bus/pci/devices/DDDD:BB:dd.f/sriov_numvfs >>> # echo 0 > /sys/bus/pci/drivers_autoprobe >>> # echo 2 > /sys/bus/pci/devices/DDDD:BB:dd.f/sriov_numvfs >>> # echo 1 > /sys/bus/pci/drivers_autoprobe >>> >>> If not, can you contrast the above with drivers_autoprobe? If we need >>> both, should they be named more similarly? >> Hi Bjorn, >> >> I agree with Alex about not using driver_autoprobe to achieve this. >> It will affect all pci related device once it's disabled(probably in >> a bad way). > Alex mooted the idea of a generic driver core knob for devices that > create child devices. That's intriguing. What other situations > besides SR-IOV do this? Maybe we could add a "drivers_autoprobe" > inside the directory of each device that's capable of having child > devices? This seems interesting to me as well. Not sure if USB driver is applicable or not. And, drivers_autoprobe might work for USB if it doesn't probe the sub-device as default like sriov. Worth to take a look. > If we continue with the current approach (instead of Alex's idea), > I propose that you: > > - Name your new knob "sriov_drivers_autoprobe" to be consistent with > other sriov sysfs files while also being parallel to > "drivers_autoprobe" > > - Update Documentation/ABI/testing/sysfs-bus-pci to document your > new knob > > - Update Documentation/ABI/... to document drivers_autoprobe Ack, will send v3. Thanks, Bodong