Hi. Would like to ask about latency
Why going below 0.2s will hurt your income and everyone else's on P2Pool. ?
What is the reason of that?
It doesn't.
It does because lowering the getblocktemplate latency is a tradeoff.
As explained in the guide with current bitcoind version reducing this latency is done by reducing the number of transactions you include in the template. Doing so you reduce the fees included in the blocks you find : you reduce your own income and everyone else's when this happens.
Today this latency has only a negative effect when a new block is found by the whole network (every ~10 minutes) unless you have a very weak CPU (where CPU usage by bitcoind can slow down P2Pool).
This is the same effect for P2Pool and every other pool : until a getblocktemplate returns a result after a new block, the pool can only work on an empty template (no transaction). Going below 0.2s only tries to reduce this 0.2/600 = 0.03% negative impact on the fees income (the block reward isn't impacted) : including more transactions (which amounts to ~1% of the average block value) simply brings more income to everyone including yourself.
Continuing the discussion about the getBlockTemplate latency...
I see quite a few public nodes have getBlockTemplate latencies approaching that magic 0.2 mark... but I've always struggled.
My p2pool node used to be in the 1.5 to 2.0 range until about a month ago when I tweaked it further per your guide and other suggestions on the net. That brought it down to the 0.5 to 0.7 range while trying to retain a high blockmaxsize for greater income.
Lately (or it seems right when the whole Bitcoin DDOS started happening in the last week), my latencies have bumped back up to the 1.0 range with occasional spikes much higher. So let's discount that bump up for now.
My real question is the efficacy of the dbcache and datadir settings. I've upped my dbcache from the default 25 to 1000. I have quite a bit of free memory to use, but not quite enough to host the entire Blockchain on a ramdrive, so datadir is probably out. Will I see any gains on getBlockTemplate Latency from upping dbcache further to lets say 2000, 3000, or even 5000 megabytes?
The Blockchain (as well as the OS and Apps) are all on an SSD already, running OSX Mavericks and using the Bitcoin-QT OMG10 0.8.5 client (waiting for the official 0.9 client to be out before I upgrade since OMG10 already has most of what went into 0.8.6 and I can't find a binary download for the Mac version of the 0.9 preview release) with wallet disabled.
Connection is over Verizon FiOS 75/35 and the Mac Pro is connected to my managed switch with dual gigabit ethernet with Link Aggregation.
Here's my bitcoin.conf (with certain parameters redacted of course):
rpcuser=XXXXREDACTEDXXXX
rpcpassword=XXXXREDACTEDXXXX
server=1
rpcport=8332
disablewallet=1
dbcache=1000
maxconnections=26
blockmaxsize=1000000
mintxfee=0.00001
minrelaytxfee=0.00001
addnode=67.186.224.85
addnode=88.198.58.172
