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WICG / turtledove

TURTLEDOVE
https://wicg.github.io/turtledove/
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multi-seller auction vs on-device resources #1186

Open jonasz opened 5 months ago

jonasz commented 5 months ago

Hi all,

In Mode B we're primarily observing single-seller auctions. Long term, we are expecting there to be multiple sellers in each PA auction.

In my understanding, in a multi-seller setting, the amount of computation will scale as number_of_buyers times number_of_sellers.

This will have a big impact on the amount of resources required to convey a full on-device auction. Publishers (or sellers who run the toplevel auction on their behalf) will face a tradeoff: either the latency will grow considerably (hurting UX and ad effectiveness), or they will have to impose stricter limits on the auction, possibly limiting buyers' and sellers' ability to take part in PA auctions.

We'd like to gain confidence that this won't happen. Unfortunately, as noted at the beginning, this is not something we can verify in the ongoing tests.

Please let me know, what are your thoughts on this?

Best regards, Jonasz

MattMenke2 commented 5 months ago

If all sellers work with all buyers, that is true. If each seller works with a distinct set of buyers, or each buyer works with at most some fixed constant number of sellers, it's just the sum of the number of buyers (Edit: Times that constant factor, of course).

jonasz commented 5 months ago

Hi Matt. Of course your comment is mathematically correct, but this is exactly what we're worried about! One worry is that sellers will have to limit the number of buyers they work with, and another is that the number of sellers taking part in an auction will have to be reduced as well. How can we, as a buyer, make sure that we will continue to have access to inventory? How can we make sure this access is diverse and robust?

dmdabbs commented 4 months ago

Indeed. Nascent B&A is adding seller control over IG data shipped off-device...

https://issues.chromium.org/issues/332299012 This feature allows sellers to customize the contents of Bidding and Auction Server requests by specifying a maximum size or selecting a set of allowed bidders and specifying the size of the resulting request (which is always padded up to that size).

Explainer PR describing the API https://github.com/WICG/turtledove/pull/1183/files?short_path=dd37a73#diff-dd37a7303a5ab6ddc1ada28f6f03865f072c2d0f10e860f9f2e1c02b0aea03dc

So on top of the existing perBuyerGroupLimits, sellers will control how much of each buyer's data is encoded, compressed and encrypted to be shipped off-device to B&A auction TEE nirvana.