On 30.05.25 11:26, Michal Hocko wrote:
On Fri 30-05-25 11:11:40, David Hildenbrand wrote:
On 30.05.25 11:07, Michal Hocko wrote:
On Fri 30-05-25 10:39:39, David Hildenbrand wrote:
On 30.05.25 10:28, Michal Hocko wrote:
[...]
All that being said I would go with an additional parameter to the
kdump cma setup - e.g. cma_sane_dma that would skip waiting and use 10s
otherwise. That would make the optimized behavior opt in, we do not need
to support all sorts of timeouts and also learn if this is not
sufficient.
Makes sense?
Just so I understand correctly, you mean extending the "crashkernel=" option
with a boolean parameter? If set, e.g., wait 1s, otherwise magic number 10?
crashkernel=1G,cma,cma_sane_dma # no wait on transition
But is no wait ok? I mean, any O_DIRECT with any device would at least take
a bit, no?
Of course, there is a short time between the crash and actually triggerying
kdump.
This is something we can test for and if we need a short timeout in this
case as well then it is just trivial to add it. I am much more
concerned about those potentially unpredictable DMA transfers that could
take too long and it is impossible to test for those and therefore we
need to overshoot.
Agreed.
--
Cheers,
David / dhildenb
