[PATCH v3 0/8] Support DEVICE_GENERIC memory in migrate_vma_*
Sierra Guiza, Alejandro (Alex)
alex.sierra at amd.com
Sat Jul 17 19:54:06 UTC 2021
On 7/16/2021 5:14 PM, Felix Kuehling wrote:
> Am 2021-07-16 um 11:07 a.m. schrieb Theodore Y. Ts'o:
>> On Wed, Jun 23, 2021 at 05:49:55PM -0400, Felix Kuehling wrote:
>>> I can think of two ways to test the changes for MEMORY_DEVICE_GENERIC in
>>> this patch series in a way that is reproducible without special hardware and
>>> For the reference counting changes we could use the dax driver with hmem and
>>> use efi_fake_mem on the kernel command line to create some DEVICE_GENERIC
>>> pages. I'm open to suggestions for good user mode tests to exercise dax
>>> functionality on this type of memory.
>> Sorry for the thread necromancy, but now that the merge window is
> No worries. Alejandro should have a new version of this series in a few
> days, with updates to hmm_test and some fixes.
V4 patch series have been sent for review.
>> Today I test ext4's dax support, without having any $$$ DAX hardware,
>> by using the kernel command line "memmap=4G!9G:memmap=9G!14G" which
>> reserves memory so that creates two pmem device and then I run
>> xfstests with DAX enabled using qemu or using a Google Compute Engine
>> VM, using TEST_DEV=/dev/pmem0 and SCRATCH_DEV=/dev/pmem1.
>> If you can give me a recipe for what kernel configs I should enable,
>> and what magic kernel command line arguments to use, then I'd be able
>> to test your patch set with ext4.
> That would be great!
> Regarding kernel config options, it should be the same as what you're
> using for DAX testing today. We're not changing or adding any Kconfig
> options. But let me take a stab:
> DEVICE_PRIVATE (maybe not needed for your test)
> I'm not sure what you're looking for in terms of kernel command line,
> other than the memmap options you already found. There are some more
> options to run hmm_test with fake SPM (DEVICE_GENERIC) memory, but we're
> already running that ourselves. That will also be in the next revision
> of this patch series.
In order to run hmm test with generic device type enabled, set the
Kernel parameters to fake SP memory. The addresses set here are based on
my system's usable memory enumerated by BIOS-e820 at boot. The test
requires two SP devices of at least 256MB.
efi_fake_mem=1G at 0x100000000:0x40000,1G at 0x140000000:0x40000
To run the hmm_test in generic device type pass the SP addresses to the
sudo ./test_hmm.sh smoke 0x100000000 0x140000000
> If you can run your xfstests with DAX on top of this patch series, that
> would be very helpful. That's to make sure the ZONE_DEVICE page refcount
> changes don't break DAX.
>> - Ted
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