Re: [PATCH v3 0/2] arm64: kdump: Function supplement and performance optimization

[john . p . donnelly]

On 8/1/22 9:47 PM, Leizhen (ThunderTown) wrote:
> On 2022/8/1 16:20, Baoquan He wrote:
> > Hi Catalin,
> >
> > On 07/11/22 at 05:03pm, Zhen Lei wrote:
> > > v2 --> v3:
> > > 1. Discard patch 3 in v2, a cleanup patch.
> > >
> > > v1 --> v2:
> > > 1. Update the commit message of Patch 1, explicitly indicates that "crashkernel=X,high"
> > >     is specified but "crashkernel=Y,low" is not specified.
> > > 2. Drop Patch 4-5. Currently, focus on function integrity, performance optimization
> > >     will be considered in later versions.
> > > 3. Patch 3 is not mandatory, it's just a cleanup now, although it is a must for patch 4-5.
> > >     But to avoid subsequent duplication of effort, I'm glad it was accepted.
> > >
> > >
> > > v1:
> > > After the basic functions of "support reserving crashkernel above 4G on arm64
> > > kdump"(see https://urldefense.com/v3/__https://lkml.org/lkml/2022/5/6/428__;!!ACWV5N9M2RV99hQ!ORBFa4UAmMss_79nuwu1kpW3D-mTela240vFo0FXOuV9QpGWy7Fp2H81ZjLPOuaufAQC_XBFEFGjAqs5njfGS6Rd4dZLhaez$ ) are implemented, we still have
> > > three features to be improved.
> > > 1. When crashkernel=X,high is specified but crashkernel=Y,low is not specified,
> > >     the default crash low memory size is provided.
> > > 2. For crashkernel=X without '@offset', if the low memory fails to be allocated,
> > >     fall back to reserve region from high memory(above DMA zones).
> > > 3. If crashkernel=X,high is used, page mapping is performed only for the crash
> > >     high memory, and block mapping is still used for other linear address spaces.
> > >     Compared to the previous version:
> > >     (1) For crashkernel=X[@offset], the memory above 4G is not changed to block
> > >         mapping, leave it to the next time.
> > >     (2) The implementation method is modified. Now the implementation is simpler
> > >         and clearer.
> >
> > Do you have plan to pick this series so that it can be taken into 5.20
> > rc-1~3?
>
> Hi, Catalin:
>    Only function reserve_crashkernel() is modified in these two patches. The core
> process of the arm64 architecture is not affected. I remember you suggested that
> arm64 and x86 share the same kdump code, so these two subfeatures are needed.
> Maybe we can lay the foundation first for the people who build the road. Unifying
> the external interfaces of kdump on arm64 and x86 does not seem to hurt.
>
>
> > We have back ported the basic crashkernel=high, low, support into our
> > distros and have taken wide testing on arm64 servers, need this patchset
> > to back port for more testing.
> >
> > Thanks
> > Baoquan
> >
> > > Zhen Lei (2):
> > >    arm64: kdump: Provide default size when crashkernel=Y,low is not
> > >      specified
> > >    arm64: kdump: Support crashkernel=X fall back to reserve region above
> > >      DMA zones
> > >
> > >   .../admin-guide/kernel-parameters.txt         | 10 ++-----
> > >   arch/arm64/mm/init.c                          | 28 +++++++++++++++++--
> > >   2 files changed, 28 insertions(+), 10 deletions(-)
> > >
> > > --
> > > 2.25.1
> >
> > .
Hi ,

What is the progress of this series ?

Without this patch set we are seeing  larger crashkernel=896M failures 
on Arm  with Linux-6.0.rc7.  This larger value is needed for
iSCSI booted systems with certain network adapters.


Thank you,
John.