Re: [RFC PATCH 4/4] i40e: don't open i40iw client for kdump

[Coiby Xu]

Hi Bhupesh,

Glad to meet you here:)

On Thu, Feb 25, 2021 at 03:41:55PM +0530, Bhupesh SHARMA wrote:
> Hello Coiby,
>
> On Mon, Feb 22, 2021 at 12:40 PM Coiby Xu <coxu@xxxxxxxxxx> 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@xxxxxxxxxx>
> > ---
> >  drivers/net/ethernet/intel/i40e/i40e_client.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/intel/i40e/i40e_client.c b/drivers/net/ethernet/intel/i40e/i40e_client.c
> > index a2dba32383f6..aafc2587f389 100644
> > --- a/drivers/net/ethernet/intel/i40e/i40e_client.c
> > +++ b/drivers/net/ethernet/intel/i40e/i40e_client.c
> > @@ -4,6 +4,7 @@
> >  #include <linux/list.h>
> >  #include <linux/errno.h>
> >  #include <linux/net/intel/i40e_client.h>
> > +#include <linux/crash_dump.h>
> >
> >  #include "i40e.h"
> >  #include "i40e_prototype.h"
> > @@ -741,6 +742,12 @@ int i40e_register_client(struct i40e_client *client)
> >  {
> >         int ret = 0;
> >
> > +       /* Don't open i40iw client for kdump because i40iw will consume huge
> > +        * amounts of memory.
> > +        */
> > +       if (is_kdump_kernel())
> > +               return ret;
> > +
>
> Since crashkernel size can be manually set on the command line by a
> user, and some users might be fine with a ~300M memory usage by i40iw
> client [with resource_profile=2"], in my view, disabling the client
> for all kdump cases seems too restrictive.
>
> We can probably check the crash kernel size allocated (
> $ cat /sys/kernel/kexec_crash_size) and then make a decision
> accordingly, so for example something like:
>
> +       if (is_kdump_kernel() && kexec_crash_size < 512M)
> +               return ret;
>
> What do you think?

Thanks for the suggestion! After having a discussion with the team, we
think it's better to not intervene i40iw in the kernel space. Actually 
when kexec-tools is building initramfs for kdump, i40iw is not included 
by default unless a user explicitly asks to include i40iw by changing 
/etc/kdump.conf, i.e., adding 'dracut_args --add-drivers "i40iw"'.


> Regards,
> Bhupesh
>
> >         if (!client) {
> >                 ret = -EIO;
> >                 goto out;
> > --
> > 2.30.1
> >
> >
> > _______________________________________________
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> > kexec@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/kexec

--
Best regards,
Coiby