On 19/08/2025 14:39, Christoph Hellwig wrote:
On Tue, Aug 19, 2025 at 12:42:01PM +0100, John Garry wrote:
nothing has been happening on this thread for a while. I figure that it is
because we have no good or obvious options.
I think that it's better deal with the NVMe driver handling of AWUPF first,
as this applies to block fops as well.
As for the suggestion to have an opt-in to use AWUPF, you wrote above that
users may not know when to enable this opt-in or not.
It seems to me that we can give the option, but clearly label that it is
potentially dangerous. Hopefully the $RANDOMUSER with the $CHEAPO SSD will
be wise and steer clear.
If we always ignore AWUPF, I fear that lots of sound NVMe implementations
will be excluded from HW atomics.
I think ignoring AWUPF is a good idea, but I've also hard some folks
not liking that.
Disabling reading AWUPF would be the best way to know that for sure :)
The reason why I prefer a mount option is because we add that to fstab
and the kernel command line easily. For block layer or driver options
we'd either need a sysfs file which is always annoying to apply at boot
time,
Could system-udev auto enable for us via sysfs file or ioctl?
or a module option which has the downside of applying to all
devices.
About the mount option, I suppose that it won't do much harm - it's just
a bit of extra work to configure.
I just fear that admins will miss enabling it or not enable it out of
doubt and users won't see the benefit of HW atomics.
