Hi Benjamin, My replies are below On Tue, Mar 23, 2021 at 05:52:33PM +1000, Erwin van Londen wrote: >> Hello All, >> > >Just wondering if there were any plans to incorporate FPIN > >congestion/latency notifications in dm-multipath to disperse IO over > >non-affected paths. > >For whats worth, general support in Kernel for a new path state in answer to existing FPIN notifications was added earlier this year: >https://lore.kernel.org/linux-scsi/1609969748-17684-1-git-send-email-mune endra.kumar@xxxxxxxxxxxx/T/ >But this only adds a new port-state and support of it for one particular driver (lpfc). Not aware of any other driver supporting this new state yet, but I might have missed it. Also, the port-state is not set in kernel, but has to be set by something external, unlike with RSCNs, where we set the >state in the kernel. We had a discussion with Marvel and they are adding the support in their(qlaxx) driver. >What it does, once a path is set into 'Marginal' state, is to not retry commands on the same shaky path, once it already failed one time already. Yes >As far as dm-multipath is concerned, I asked that as well when this patch series was developed: >https://lore.kernel.org/linux-scsi/20201002162633.GA8365@t480-pf1aa2c2/ >Hannes answered that in the thread: >https://lore.kernel.org/linux-scsi/ca995d96-608b-39b9-8ded-4a6dd7598660@s use.de/ >Not sure what happened in between, didn't see anything on the mpath topic yet. As Hannes mentioned in his reply we have an external daemon called fctxpd which acts on fpin-li events and sets the path to marginal path group as well as set the port state to marginal. This daemon is part of epel8. Below is the path for the same where we have changes https://github.com/brocade/bsn-fc-txptd The above code is reviewed by the Benjamin Marzinski from redhat . Note:The latest release will be available on the epel8 where we have the support to set the port state to marginal in a week time As we have all the support in the kernel for fpin registration, notifications and also setting the port_state to marginal We had a initial discussion with Hannes adding the fpin based native support in dm multipathd for FPIN Congestion/Latency notifications . I will take the initiative and start the discussion with Benjamin Marzinski and get this work done with the help of Hannes. Regards, Muneendra. -- This electronic communication and the information and any files transmitted with it, or attached to it, are confidential and are intended solely for the use of the individual or entity to whom it is addressed and may contain information that is confidential, legally privileged, protected by privacy laws, or otherwise restricted from disclosure to anyone else. If you are not the intended recipient or the person responsible for delivering the e-mail to the intended recipient, you are hereby notified that any use, copying, distributing, dissemination, forwarding, printing, or copying of this e-mail is strictly prohibited. If you received this e-mail in error, please return the e-mail to the sender, delete it from your computer, and destroy any printed copy of it.
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