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Date:   Wed, 24 Feb 2021 08:48:41 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     Coiby Xu <coxu@redhat.com>
Cc:     netdev@vger.kernel.org, kexec@lists.infradead.org,
        intel-wired-lan@lists.osuosl.org,
        Jesse Brandeburg <jesse.brandeburg@intel.com>,
        Tony Nguyen <anthony.l.nguyen@intel.com>,
        "David S. Miller" <davem@davemloft.net>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 4/4] i40e: don't open i40iw client for kdump
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References: <20210222070701.16416-1-coxu@redhat.com>
        <20210222070701.16416-5-coxu@redhat.com>
        <20210223122207.08835e0b@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
        <20210224114141.ziywca4dvn5fs6js@Rk>
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On Wed, 24 Feb 2021 19:41:41 +0800 Coiby Xu wrote:
> On Tue, Feb 23, 2021 at 12:22:07PM -0800, Jakub Kicinski wrote:
> >On Mon, 22 Feb 2021 15:07:01 +0800 Coiby Xu wrote:  
> >> i40iw consumes huge amounts of memory. For example, on a x86_64 machine,
> >> i40iw consumed 1.5GB for Intel Corporation Ethernet Connection X722 for
> >> for 1GbE while "craskernel=auto" only reserved 160M. With the module
> >> parameter "resource_profile=2", we can reduce the memory usage of i40iw
> >> to ~300M which is still too much for kdump.
> >>
> >> Disabling the client registration would spare us the client interface
> >> operation open , i.e., i40iw_open for iwarp/uda device. Thus memory is
> >> saved for kdump.
> >>
> >> Signed-off-by: Coiby Xu <coxu@redhat.com>  
> >
> >Is i40iw or whatever the client is not itself under a CONFIG which
> >kdump() kernels could be reasonably expected to disable?
> >  
> 
> I'm not sure if I understand you correctly. Do you mean we shouldn't
> disable i40iw for kdump?

Forgive my ignorance - are the kdump kernels separate builds?

If they are it'd be better to leave the choice of enabling RDMA 
to the user - through appropriate Kconfig options.