Quote from: o_e_l_e_o on Today at 11:06:30 AM

Quote from: vv181 on Today at 10:36:40 AM

So that is what the Sparrow's Premix Fee Rate is supposed to do, right? Things that make the postmix-ed UTXOs able to be remixed repeatedly and the coinjoin that has more than 5-input-5-output is come from that premix fee, if the current pool participant/condition has a low fee that would reduce the number of inputs and postmix remix rounds availability. Am I understand it correctly?

Each Whirlpool coinjoin has two inputs which are brand new entries to the pool, and these are the two that pay that transaction fee for the coinjoin. In a 5-input-5-output coinjoin, then 3 UTXOs will be free remixes. In an 8-and-8 coinjoin, then it will be 6 UTXOs which will be free remixes. So yeah, if there is a majority of 5-and-5 coinjoins, then the relative speed of free remixes will be slower than if there was a majority of 8-and-8, for example.

Having said that, I don't know if it is these new larger coinjoins, if it is more and more people using Whirlpool, if it is just my own bias, or some combination of all of these, but I am getting more free remixes more quickly these days than I did, say, a year ago.

All right, so what the Sparrow's Premix Fee Rate do is to set 2 things. First, to set the Tx0 miner fee, and second, for the miner fee contribution (premixer, the one who pays the fee of the coinjoin tx).

Things started to get clear after I read your explanation and Introducing Whirlpool Surge Cycles.

Quote from: https://blog.samourai.is/introducing-whirlpool-surge-cycles/#coinjoin-transaction-inputs

2 x Premixer UTXOs from separate wallets*
3 x Remixing UTXOs from separate wallets

Premixers are new entrants into Whirlpool, and are those who cover the miner fee for the CoinJoin transaction. Remixers are those who have already entered Whirlpool, completed their first mix already, and are now “freeriding” to obtain more mixes.

So in the event that the on-chain fees dropped while the user had broadcasted/initiated the transaction with some set of Cycle Priority(miner fee contribution). Whirlpool coordinator adjusts/make-use-of the, if there are any, excess transaction fees by adding up more input/output. With a minimum of 5-inputs/5-outputs and a maximum of 8-inputs/8-outputs.

Anyway, the reason I am trying to figure out is that I recently made my first coinjoin transaction, and the result was unexpected since it cost some hidden fees, like other experienced. I thought the unadjustable premix fee rate was the culprit since it only able spent 5 times of the mempool fee rate. Turns out, it's just how it works. I also didn't consider the miner fees. Reading up all about that I also found a site to help calculate detailed Whirlpool fees: https://bitcoiner.guide/wpfees/. So yeah that's about it.