[Ethereum] How does Ethereum avoid inaccurate timestamps in blocks

If you are using geth here's a patch that I use to accelerate mining. You could probably modify it to decelerate mining if you wish. (I'm curious why you wish to go slower). In any event, I think the answer to "how does the interval for mining get set" is "not very clear from the code"... but this patch should give you a head start in understanding the timing of geth.

diff --git a/eth/fetcher/fetcher.go b/eth/fetcher/fetcher.go
index d88d919..f03fd30 100644
--- a/eth/fetcher/fetcher.go
+++ b/eth/fetcher/fetcher.go
@@ -34,7 +34,7 @@ import (
 const (
    arriveTimeout = 500 * time.Millisecond // Time allowance before an announced block is explicitlrd
    gatherSlack   = 100 * time.Millisecond // Interval used to collate almost-expired announces witfs
-   fetchTimeout  = 5 * time.Second        // Maximum alloted time to return an explicitly requestebk
+   fetchTimeout  = 1 * time.Second        // Maximum alloted time to return an explicitly requestebk
    maxUncleDist  = 7                      // Maximum allowed backward distance from the chain head
    maxQueueDist  = 32                     // Maximum allowed distance from the chain head to queue
    hashLimit     = 256                    // Maximum number of unique blocks a peer may have annoued
diff --git a/eth/peer.go b/eth/peer.go
index 15ba22f..0201057 100644
--- a/eth/peer.go
+++ b/eth/peer.go
@@ -41,7 +41,7 @@ var (
 const (
    maxKnownTxs      = 32768 // Maximum transactions hashes to keep in the known list (prevent DOS)
    maxKnownBlocks   = 1024  // Maximum block hashes to keep in the known list (prevent DOS)
-   handshakeTimeout = 5 * time.Second
+   handshakeTimeout = 1 * time.Second
 )

 // PeerInfo represents a short summary of the Ethereum sub-protocol metadata known
diff --git a/miner/worker.go b/miner/worker.go
index 754a6fc..2b62b59 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -466,7 +466,7 @@ func (self *worker) commitNewWork() {
            tstamp = parent.Time().Int64() + 1
    }
    // this will ensure we're not going off too far in the future
-   if now := time.Now().Unix(); tstamp > now+4 {
+   if now := time.Now().Unix(); tstamp > now {
            wait := time.Duration(tstamp-now) * time.Second
            glog.V(logger.Info).Infoln("We are too far in the future. Waiting for", wait)
            time.Sleep(wait)
diff --git a/p2p/rlpx.go b/p2p/rlpx.go
index aaa7338..ce82eb7 100644
--- a/p2p/rlpx.go
+++ b/p2p/rlpx.go
@@ -57,7 +57,7 @@ const (

    // total timeout for encryption handshake and protocol
    // handshake in both directions.
-   handshakeTimeout = 5 * time.Second
+   handshakeTimeout = 2 * time.Second

    // This is the timeout for sending the disconnect reason.
    // This is shorter than the usual timeout because we don't want
diff --git a/params/protocol_params.go b/params/protocol_params.go
index dcc17e0..21a49c5 100755
--- a/params/protocol_params.go
+++ b/params/protocol_params.go
@@ -29,10 +29,10 @@ var (
    CallNewAccountGas      = big.NewInt(25000)  // Paid for CALL when the destination address didn'e.
    TxGas                  = big.NewInt(21000)  // Per transaction. NOTE: Not payable on data of cas.
    TxDataZeroGas          = big.NewInt(4)      // Per byte of data attached to a transaction that u.
-   DifficultyBoundDivisor = big.NewInt(2048)   // The bound divisor of the difficulty, used in thep.
+   DifficultyBoundDivisor = big.NewInt(1)      // The bound divisor of the difficulty, used in thep.
    QuadCoeffDiv           = big.NewInt(512)    // Divisor for the quadratic particle of the memoryo.
-   GenesisDifficulty      = big.NewInt(131072) // Difficulty of the Genesis block.
-   DurationLimit          = big.NewInt(13)     // The decision boundary on the blocktime duration e.
+   GenesisDifficulty      = big.NewInt(1)      // Difficulty of the Genesis block.
+   DurationLimit          = big.NewInt(1)      // The decision boundary on the blocktime duration e.
    SstoreSetGas           = big.NewInt(20000)  // Once per SLOAD operation.
    LogDataGas             = big.NewInt(8)      // Per byte in a LOG* operation's data.
    CallStipend            = big.NewInt(2300)   // Free gas given at beginning of call.
@@ -57,7 +57,7 @@ var (
    CreateDataGas        = big.NewInt(200)    //
    Ripemd160Gas         = big.NewInt(600)    //
    Ripemd160WordGas     = big.NewInt(120)    //
-   MinimumDifficulty    = big.NewInt(131072) // The minimum that the difficulty may ever be.
+   MinimumDifficulty    = big.NewInt(1)      // The minimum that the difficulty may ever be.
    CallCreateDepth      = big.NewInt(1024)   // Maximum depth of call/create stack.
    ExpGas               = big.NewInt(10)     // Once per EXP instuction.
    LogGas               = big.NewInt(375)    // Per LOG* operation.

I don't think there's currently a way to do this. (Either in Remix or in the Solidity code directly.)

The following open issues are relevant. You might want to follow them on GitHub directly:

• #2675: Be able to disable all warnings for certain files
• #2691: Allow comments to ignore compiler warnings.