The gas price oracle is a helper function of the Geth client that tries to find an appropriate default gas price when sending transactions. It can be parametrized with the following command line options:

- gpomin: lower limit of suggested gas price. This should be set at least as high as the "gasprice" setting usually used by miners so that your transactions will not be rejected automatically because of a too low price.

- gpomax: higher limit of suggested gas price. During load peaks when there is a competition between transactions to get into the blocks, the price needs to be limited, otherwise the oracle would eventually try to overbid everyone else at any price.

- gpofull: a block is considered "full" when a certain percentage of the block gas limit (specified in percents) is used up by transactions. If a block is not "full", that means that a transaction could have been accepted even with a minimal price offered.

- gpobasedown: an exponential ratio (specified in 1/1000ths) by which the base price decreases when the lowest acceptable price of the last block is below the last base price.

- gpobaseup: an exponential ratio (specified in 1/1000ths) by which the base price increases when the lowest acceptable price of the last block is over the last base price.

- gpobasecf: a correction factor (specified in percents) of the base price. The suggested price is the corrected base price, limited by gpomin and gpomax.

The lowest acceptable price is defined as a price that could have been enough to insert a transaction into a certain block. Although this value varies slightly with the gas used by the particular transaction, it is aproximated as follows: if the block is full, it is the lowest transaction gas price found in that block. If the block is not full, it equals to gpomin.

The base price is a moving value that is adjusted from block to block, up if it was lower than the lowest acceptable price, down otherwise. Note that there is a slight amount of randomness added to the correction factors so that your client will not behave absolutely predictable on the market.

If you want to specify a constant for the default gas price and not use the oracle, set both gpomin and gpomax to the same value.