netdev - Re: [PATCH net-next 0/9] devlink: Add support for region access

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Date:   Wed, 4 Apr 2018 14:07:08 +0300
From:   Alex Vesker <valex@...lanox.com>
To:     David Ahern <dsahern@...il.com>, Andrew Lunn <andrew@...n.ch>
CC:     "David S. Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>,
        "Tariq Toukan" <tariqt@...lanox.com>,
        Jiri Pirko <jiri@...lanox.com>
Subject: Re: [PATCH net-next 0/9] devlink: Add support for region access



On 3/31/2018 8:21 PM, David Ahern wrote:
> On 3/31/18 9:53 AM, Andrew Lunn wrote:
>>> I want to be able to login to a customer and accessing this snapshot
>>> without any previous configuration from the user and not asking for
>>> enabling the feature and then waiting for a repro...this will help
>>> debugging issues that are hard to reproduce, I don't see any reason
>>> to disable this.
>> The likely reality is 99.9% of these snapshots will never be seen or
>> used. But they take up memory sitting there doing nothing. And if the
>> snapshot is 2GB, that is a lot of memory. I expect a system admin
>> wants to be able to choose to enable this feature or not, because of
>> that memory. You should also consider implementing the memory pressure
>> callbacks, so you can discard snapshots, rather than OOM the machine.
>>
> That is exactly my point. Nobody wants one rogue device triggering
> snapshots, consuming system resources and with no options to disable it.


OK, currently there is a task to support persistent/permanent configuration
to devlink. Once this support is in I will add my code on top of it.
This will allow a user to enable the snapshot functionality on the driver.
Regarding the double continuous allocation of memory, I will fix to a single
vmalloc on the driver in case of adding a snapshot. Tell me what you think.