On Thu, 29 Aug 2019 03:47:02 +0000 Nitin Katiyar <nitin.kati...@ericsson.com> wrote:
> > -----Original Message----- > > From: Stephen Hemminger [mailto:step...@networkplumber.org] > > Sent: Wednesday, August 28, 2019 1:43 AM > > To: Nitin Katiyar <nitin.kati...@ericsson.com> > > Cc: dev@dpdk.org; Venkatesan Pradeep > > <venkatesan.prad...@ericsson.com> > > Subject: Re: [dpdk-dev] [PATCH 1/2] bus/pci: Fail rte_pci_probe if probing > > all > > whitelisted devices fail. > > > > On Wed, 28 Aug 2019 01:00:16 +0530 > > Nitin Katiyar <nitin.kati...@ericsson.com> wrote: > > > > > Even if whitelist of devices is provided, rte_pci_probe() increments > > > the probed counter for all the devices present in the system. If probe > > > fails for all the whitelisted devices it still return success because > > > failed and probed counts don't match. > > > > > > This patch increments probed count only when devices are actually > > > probed. > > > > > > Signed-off-by: Nitin Katiyar <nitin.kati...@ericsson.com> > > > Signed-off-by: Venkatesan Pradeep <venkatesan.prad...@ericsson.com> > > > > There are two differing interpretations of this. > > The simple case which is what your patch fixes is where user gives bad > > arguments and no devices are present. > > > > But the more complex case is where the devices show up later via hotplug or > > other discovery mechanism. For example, on Hyper-V/Azure SRIOV PCI > > devices can show up after application is started. Your patch might break > > the > > use case of where an application is started before the VF is available. > > > > More detailed example: > > > > 1. VM is started. > > 2. VF is take offline for maintenance or migration. > > 3. DPDK application is started with whitelist option (no usable PCI found). > > 4. VF becomes available after maintenance. > > > > Yes, this a somewhat made up order which is unlikely to happen in real life. > > But there is nothing stopping it from happening. > > > > I often recommend to customers using whitelist because the typical appliance > > scenario has a management interface, and you don't want the DPDK > > interacting with the VF of the management interface. > > > > Therefore, from my point of view, this patch is a NO. > Hi, > Thanks for your comments. I am sorry I couldn't understand the scenario you > mentioned. > > If we are not probing the device then why should we be incrementing the > probed counter. If current implementation doesn't handle the scenario where > all the devices in concern failed in probe (as per the whitelist) and code > fails to catch that case. Application like OVS using DPDK comes up > successfully although it doesn't have any physical device in usable state. > > Best regards, > Nitin > When application starts there maybe no PCI devices, but PCI devices arrive later via hotplug.
