[Devel] Re: [PATCH 2/3] epoll: Add support for checkpointing large numbers of epoll items

[Oren Laadan]

Matt Helsley wrote:
> Currently we allocate memory to output all of the epoll items in one
> big chunk. At 20 bytes per item, and since epoll was designed to
> support on the order of 10,000 items, we may find ourselves kmalloc'ing
> 200,000 bytes. That's an order 7 allocation whereas the heuristic for
> difficult allocations, PAGE_ALLOC_COST_ORDER, is 3.
> 
> Instead, output the epoll header and items separately. Chunk the output
> much like the pid array gets chunked. This ensures that even sub-order 0
> allocations will enable checkpoint of large epoll sets. A subsequent
> patch will do something similar for the restore path.
> 
> Signed-off-by: Matt Helsley <matthltc at us.ibm.com>

Acked-by: Oren Laadan <orenl at cs.columbia.edu>

BTW, In the future, please use checkpatch.pl before sending;
Otherwise eventually I get yelled at ... :p

I'll fix this patchset as I pull.

I'll also change the auto-tune-magic to fixed chunk, unless
somebody screams.

Oren.


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