Transaction

j"1LAnZuoQdcKCkpDBKQMCgziGMoPC4VQUckM?<div class="post"><div class="quoteheader"><a href="https://bitcointalk.org/index.php?topic=1332.msg14960#msg14960">Quote from: lzsaver on October 02, 2010, 05:49:47 AM</a></div><div class="quote">Can you tell more about it:<br/>"they have to do weird things with extraNonce, which increases the size of the block header".<br/></div><br/>When you generate, you calculate hashes of the block header. Hashing more data is slower than hashing less data, so the block header is critically of a fixed size for everyone, with one exception. After every hash attempt, you increment the Nonce header field, but since this field is only 32 bytes long, it overflows a lot. Whenever it overflows, you increment the variable-size extraNonce field. The larger extraNonce gets, the slower generating will get. It doesn't get significantly large with normal incrementing, though.<br/><br/>If you have a lot of computers and they're all working on the same block with the same public key, then they're all very likely to be hashing the same block at the same time, which is pointless. To fix this, each computer is given a unique extraNonce modifier value. This might be very large to prevent collisions, and it therefore slows down hashing.<br/><br/>Undoubtedly you could design a pooling system without this flaw, but it'd be more difficult.<br/><br/>I see that m0mchil's getwork is doing something with extraNonce. I don't know how bad that implementation is, but it theoretically <i>must</i> be slower than a client without it (all things being equal; clearly adding GPU support will improve performance).</div> text/html