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56 lines
3.4 KiB
56 lines
3.4 KiB
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This README contains extended details about FPGA mining with cgminer |
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Icarus |
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There is a hidden option in cgminer when Icarus support is compiled in: |
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--icarus-timing <arg> Set how the Icarus timing is calculated - one setting/value for all or comma separated |
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default[=N] Use the default Icarus hash time (2.6316ns) |
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short Calculate the hash time and stop adjusting it at ~315 difficulty 1 shares (~1hr) |
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long Re-calculate the hash time continuously |
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value[=N] Specify the hash time in nanoseconds (e.g. 2.6316) and abort time (e.g. 2.6316=80) |
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Icarus timing is required for devices that do not exactly match a default Icarus Rev3 in |
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processing speed |
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If you have an Icarus Rev3 you should not normally need to use --icarus-timing since the |
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default values will maximise the MH/s and display it correctly |
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Icarus timing is used to determine the number of hashes that have been checked when it aborts |
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a nonce range (including on a LongPoll) |
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It is also used to determine the elapsed time when it should abort a nonce range to avoid |
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letting the Icarus go idle, but also to safely maximise that time |
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'short' or 'long' mode should only be used on a computer that has enough CPU available to run |
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cgminer without any CPU delays (an active desktop or swapping computer would not be stable enough) |
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Any CPU delays while calculating the hash time will affect the result |
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'short' mode only requires the computer to be stable until it has completed ~315 difficulty 1 shares |
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'long' mode requires it to always be stable to ensure accuracy, however, over time it continually |
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corrects itself |
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When in 'short' or 'long' mode, it will report the hash time value each time it is re-calculated |
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In 'short' or 'long' mode, the scan abort time starts at 5 seconds and uses the default 2.6316ns |
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scan hash time, for the first 5 nonce's or one minute (whichever is longer) |
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In 'default' or 'value' mode the 'constants' are calculated once at the start, based on the default |
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value or the value specified |
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The optional additional =N specifies to set the default abort at N 1/10ths of a second, not the |
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calculated value, which is 112 for 2.6316ns |
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To determine the hash time value for a non Icarus Rev3 device or an Icarus Rev3 with a different |
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bitstream to the default one, use 'long' mode and give it at least a few hundred shares, or use |
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'short' mode and take note of the final hash time value (Hs) calculated |
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You can also use the RPC API 'stats' command to see the current hash time (Hs) at any time |
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The Icarus code currently only works with a dual FPGA device that supports the same commands as |
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Icarus Rev3 requires and also is less than ~840MH/s and greater than 2MH/s |
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If a dual FPGA device does hash faster than ~840MH/s it should work correctly if you supply the |
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correct hash time nanoseconds value |
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The timing code itself will affect the Icarus performance since it increases the delay after |
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work is completed or aborted until it starts again |
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The increase is, however, extremely small and the actual increase is reported with the |
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RPC API 'stats' command (a very slow CPU will make it more noticeable) |
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Using the 'short' mode will remove this delay after 'short' mode completes |
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The delay doesn't affect the calculation of the correct hash time
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