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From: James Smart <jsmart2021@gmail.com>
To: Benjamin Block <bblock@linux.ibm.com>,
	Muneendra Kumar M <muneendra.kumar@broadcom.com>
Cc: Benjamin Block <lkml@mageta.org>,
	linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
	tj@kernel.org, linux-nvme@lists.infradead.org, hare@suse.de,
	emilne@redhat.com, mkumar@redhat.com,
	Steffen Maier <maier@linux.ibm.com>
Subject: Re: [PATCH v9 03/13] nvme: Added a newsysfs attribute appid_store
Date: Thu, 22 Apr 2021 16:29:10 -0700
Message-ID: <2eec720b-401a-32b4-80e6-900e136939b3@gmail.com> (raw)
In-Reply-To: <YH62VB+SVfnG+GoI@t480-pf1aa2c2.linux.ibm.com>

On 4/20/2021 4:09 AM, Benjamin Block wrote:
> On Tue, Apr 20, 2021 at 12:24:41PM +0530, Muneendra Kumar M wrote:
>> Hi Benjamin,
>>
>>>> ---
>>>>   drivers/nvme/host/fc.c | 73
>>>> +++++++++++++++++++++++++++++++++++++++++-
>>>>   1 file changed, 72 insertions(+), 1 deletion(-)
>>
>>> Hmm, I wonder why only NVMe-FC? Or is this just for the moment? We also
>>> have the FC transport class for SCSI; I assume this could feed the same
>>> IDs into the LLDs.
>>
>> At present it supports only for SCSI-FC .
> 
> It does? By adding it to the implementation under `drivers/nvme/host/`?
> I am confused.

Yeah, this is a little odd.

This history is: we know we need to merge the scsi fc transport and the 
nvme fc transport as the two independent things are creating 
difficulties and duplications (devloss is an example). But it's a bit of 
work to change this as it will move where the objects are in the 
topology tree.

As we tried to figure out how to do the interaction with cgroups, we 
wanted to support SCSI and nvme. If you look at how this new attribute 
sets the vmid, it's somewhat generic - it just sets the fc appid field 
on a cgrp id.  There's really nothing that says the cgrp is on a block 
device that is scsi or is nvme.  It should work on devices regardless of 
their underlying protocol type. Which then left the question - where to 
place such an attribute.

Given this is an "fc service" and as we knew the transport will be 
merged eventually we picked to put it under /sys/class/fc point which is 
where we expect to root the common transport. This class point happens 
to be owned/created by the nvme fc host code for requesting nve-fc 
rediscovery events. It is odd that it creates a requirement to load the 
nvme-fc transport in order to set values for scsi fc devices, but we 
deemed it acceptable.  Guess we need to get going on that merged 
transport...

-- james



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Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-06 23:06 [PATCH v9 00/13] blkcg:Support to track FC storage blk io traffic Muneendra
2021-04-06 23:06 ` [PATCH v9 01/13] cgroup: Added cgroup_get_from_id Muneendra
2021-04-08  8:26   ` Hannes Reinecke
2021-04-06 23:06 ` [PATCH v9 02/13] blkcg: Added a app identifier support for blkcg Muneendra
2021-04-08  8:26   ` Hannes Reinecke
2021-04-06 23:06 ` [PATCH v9 03/13] nvme: Added a newsysfs attribute appid_store Muneendra
2021-04-18 15:32   ` Benjamin Block
2021-04-20  6:54     ` Muneendra Kumar M
2021-04-20 11:09       ` Benjamin Block
2021-04-22 23:29         ` James Smart [this message]
2021-04-23 10:14           ` Benjamin Block
2021-04-06 23:06 ` [PATCH v9 04/13] lpfc: vmid: Add the datastructure for supporting VMID in lpfc Muneendra
2021-04-08  8:28   ` Hannes Reinecke
2021-04-06 23:06 ` [PATCH v9 05/13] lpfc: vmid: VMID params initialization Muneendra
2021-04-08  8:29   ` Hannes Reinecke
2021-04-06 23:06 ` [PATCH v9 06/13] lpfc: vmid: Add support for vmid in mailbox command, does vmid resource allocation and vmid cleanup Muneendra
2021-04-08  8:32   ` Hannes Reinecke
2021-04-06 23:06 ` [PATCH v9 07/13] lpfc: vmid: Implements ELS commands for appid patch Muneendra
2021-04-08  8:34   ` Hannes Reinecke
2021-04-20 12:38   ` Benjamin Block
2021-04-21 22:55     ` James Smart
2021-04-22  9:28       ` Benjamin Block
2021-04-06 23:06 ` [PATCH v9 08/13] lpfc: vmid: Functions to manage vmids Muneendra
2021-04-08  8:35   ` Hannes Reinecke
2021-04-06 23:06 ` [PATCH v9 09/13] lpfc: vmid: Implements CT commands for appid Muneendra
2021-04-08  8:37   ` Hannes Reinecke
2021-04-06 23:06 ` [PATCH v9 10/13] lpfc: vmid: Appends the vmid in the wqe before sending Muneendra
2021-04-06 23:06 ` [PATCH v9 11/13] lpfc: vmid: Timeout implementation for vmid Muneendra
2021-04-08  8:38   ` Hannes Reinecke
2021-04-06 23:06 ` [PATCH v9 12/13] lpfc: vmid: Adding qfpa and vmid timeout check in worker thread Muneendra
2021-04-06 23:06 ` [PATCH v9 13/13] lpfc: vmid: Introducing vmid in io path Muneendra
2021-04-08  8:46   ` Hannes Reinecke
2021-04-10 15:00     ` James Smart
2021-04-12  5:27       ` Hannes Reinecke

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