Re: [PATCH 0/5] optimize some data structure in nvme

Sagi Grimberg
2023-05-01T13:57:22Z

> This serie is a proposal to slighly optimize the memory needed for some
> structures used in nvme.
>
> This follows the discussion in [1].
>
> Honnestly, I'm not convinced that this serie really brings semething.
> Because of the way memory alocation works, and its over-allocation to try to
> avoid memory fragmentation, some limited gains are most of the time useless.
>
> It could still help:
> - many holes in structure can, at some point, have its size reach a threshold
> (this is specially true if such structures are allocated with kcalloc() or
> kmalloc_array())
> - it can save some space in some other structures if embedded in them
> - it can save a few cycles if the structure is memcpy()'ed or zeroed, for
> example
> - can reduce cache usage
>
> With that in mind, patch 3 is a win, patch 4 is likely a win, the other ones are
> much more theorical.
>
> The changes are really limited, so even if the gain is marginal, maybe it still
> makes sense to merge them.

Don't see why not, given they make do the structures smaller.

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>