On 09/20/2016 07:30 AM, David Laight wrote:
From: Jason Baron
Sent: 19 September 2016 19:34

sizeof(struct bnx2x_mcast_list_elem) = 24. So there are 170 per
page on x86. So if we want to fit 2,048 elements, we need 12 pages.

If you only need to save the mcast addresses you could use a 'heap'
that requires no overhead per entry and gives you O(log) lookup.
6 bytes per entry is 682 in a 4k page.


Indeed, that would save space here.

Based on Yuval's comments it sounds as though he agrees that it makes sense to go beyond a page (even if we get 682 per page as you suggest), when configuring these mac filters. So we would then have to allocate and manage the page pointers. Currently, there is a list_head per entry to manage the macs as a linked list. The patch I proposed continues to use that same data structure, thus it will not add to the memory footprint, it only proposes to break that footprint up into PAGE_SIZE chunks.

So I think the change you suggest can be viewed as an additional enhancement here, and also note that the memory allocations here are short-lived. That is, they only exist in memory until the NIC is re-configured.



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