jl2012 at xbt.hk [ARCHIVE] on Nostr: š Original date posted:2015-09-03 š Original message:Some comments: * The 75% ...
š
Original date posted:2015-09-03
š Original message:Some comments:
* The 75% rule is meaningless here. Since this is a pure relaxation of
rules, there is no such thing as "invalid version 4 blocks"
*
The implication threshold is unclear. Is it 95% or 80%?
* Softfork requires a very high threshold (95%) to "attack" the
original fork. This makes sure that unupgraded client will only see the
new fork.
* In the case of hardfork, however, the new fork is unable to attack
the original fork, and unupgraded client will never see the new fork.
The initiation of a hardfork should be based on its acceptance by the
economic majority, not miner support. 95% is an overkill and may
probably never accomplished. I strongly prefer a 80% threshold rather
than 95%.
* As I've pointed out, using 20-percentile rather than median creates
an incentive to 51% attack the uncooperative minority.
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-August/010690.html
Having said that, I don't have a strong feeling about the use of
20-percentile as threshold to increase the block size. That means the
block size is increased only when most miners agree, which sounds ok to
me.
However, using 20-percentile as threshold to DECREASE the block size
could be very dangerous. Consider that the block size has been stable at
8MB for a few years. Everyone are happy with that. An attacker would
just need to acquire 21% of mining power to break the status quo and
send us all the way to 1MB. The only way to stop such attempt is to 51%
attack the attacker. That'd be really ugly.
For technical and ethical reasons, I believe the thresholds for increase
and decrease must be symmetrical: increase the block size when the
x-percentile is bigger than the current size, decrease the block size
when the (100-x)-percentile is smaller than the current size. The
overall effect is: the block size remains unchanged unless 80% of miners
agree to.
* Please consider the use of "hardfork bit" to signify the hardfork:
https://www.reddit.com/r/bitcoin_devlist/comments/3ekhg2/bip_draft_hardfork_bit_jl2012_at_xbthk_jul_23_2015/
https://github.com/jl2012/bips/blob/master/hardforkbit.mediawiki
* Or, alternatively, please combine the hardfork with a softfork. I'm
rewriting the specification as follow (changes underlined):
* Replace static 1M block size hard limit with a floating limit
("hardLimit").
*
hardLimit floats within the range 1-32M, inclusive.
*
Initial value of hardLimit is 1M, preserving current system.
* Changing hardLimit is accomplished by encoding a proposed value
within a block's coinbase scriptSig.
* Votes refer to a byte value, encoded within the pattern "/BVd+/"
Example: /BV8000000/ votes for 8,000,000 byte hardLimit. If there is
more than one match with with pattern, the first match is counted.
* Absent/invalid votes and votes below minimum cap (1M) are counted as
1M votes. Votes above the maximum cap (32M) are counted as 32M votes.
* A new hardLimit is calculated at each difficult adjustment period
(2016 blocks), and applies to the next 2016 blocks.
* Calculate hardLimit by examining the coinbase scriptSig votes of the
previous 12,000 blocks, and taking the 20th percentile and 80th
percentile.
* New hardLimit is the median of the followings:
* min(current hardLimit * 1.2, 20-percentile)
* max(current hardLimit / 1.2, 80-percentile)
* current hardLimit
* version 4 block: the coinbase of a version 4 block must match this
pattern: "/BVd+/"
* 70% rule: If 8,400 of the last 12,000 blocks are version 4 or
greater, reject invalid version 4 blocks. (testnet4: 501 of last 1000)
* 80% rule ("Point of no return"): If 9,600 of the last 12,000 blocks
are version 4 or greater, reject all version <= 3 blocks. (testnet4: 750
of last 1000)
* Block version number is calculated after masking out high 16 bits
(final bit count TBD by versionBits outcome).
Jeff Garzik via bitcoin-dev ę¼ 2015-09-02 23:33 åÆ«å°:
> BIP 100 initial public draft:
> https://github.com/jgarzik/bip100/blob/master/bip-0100.mediawiki [1]
>
> Emphasis on "initial" This is a starting point for the usual open
> source feedback/iteration cycle, not an endpoint that Must Be This
> Way.
>
>
>
> Links:
> ------
> [1] https://github.com/jgarzik/bip100/blob/master/bip-0100.mediawiki
>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev at lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
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š Original message:Some comments:
* The 75% rule is meaningless here. Since this is a pure relaxation of
rules, there is no such thing as "invalid version 4 blocks"
*
The implication threshold is unclear. Is it 95% or 80%?
* Softfork requires a very high threshold (95%) to "attack" the
original fork. This makes sure that unupgraded client will only see the
new fork.
* In the case of hardfork, however, the new fork is unable to attack
the original fork, and unupgraded client will never see the new fork.
The initiation of a hardfork should be based on its acceptance by the
economic majority, not miner support. 95% is an overkill and may
probably never accomplished. I strongly prefer a 80% threshold rather
than 95%.
* As I've pointed out, using 20-percentile rather than median creates
an incentive to 51% attack the uncooperative minority.
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-August/010690.html
Having said that, I don't have a strong feeling about the use of
20-percentile as threshold to increase the block size. That means the
block size is increased only when most miners agree, which sounds ok to
me.
However, using 20-percentile as threshold to DECREASE the block size
could be very dangerous. Consider that the block size has been stable at
8MB for a few years. Everyone are happy with that. An attacker would
just need to acquire 21% of mining power to break the status quo and
send us all the way to 1MB. The only way to stop such attempt is to 51%
attack the attacker. That'd be really ugly.
For technical and ethical reasons, I believe the thresholds for increase
and decrease must be symmetrical: increase the block size when the
x-percentile is bigger than the current size, decrease the block size
when the (100-x)-percentile is smaller than the current size. The
overall effect is: the block size remains unchanged unless 80% of miners
agree to.
* Please consider the use of "hardfork bit" to signify the hardfork:
https://www.reddit.com/r/bitcoin_devlist/comments/3ekhg2/bip_draft_hardfork_bit_jl2012_at_xbthk_jul_23_2015/
https://github.com/jl2012/bips/blob/master/hardforkbit.mediawiki
* Or, alternatively, please combine the hardfork with a softfork. I'm
rewriting the specification as follow (changes underlined):
* Replace static 1M block size hard limit with a floating limit
("hardLimit").
*
hardLimit floats within the range 1-32M, inclusive.
*
Initial value of hardLimit is 1M, preserving current system.
* Changing hardLimit is accomplished by encoding a proposed value
within a block's coinbase scriptSig.
* Votes refer to a byte value, encoded within the pattern "/BVd+/"
Example: /BV8000000/ votes for 8,000,000 byte hardLimit. If there is
more than one match with with pattern, the first match is counted.
* Absent/invalid votes and votes below minimum cap (1M) are counted as
1M votes. Votes above the maximum cap (32M) are counted as 32M votes.
* A new hardLimit is calculated at each difficult adjustment period
(2016 blocks), and applies to the next 2016 blocks.
* Calculate hardLimit by examining the coinbase scriptSig votes of the
previous 12,000 blocks, and taking the 20th percentile and 80th
percentile.
* New hardLimit is the median of the followings:
* min(current hardLimit * 1.2, 20-percentile)
* max(current hardLimit / 1.2, 80-percentile)
* current hardLimit
* version 4 block: the coinbase of a version 4 block must match this
pattern: "/BVd+/"
* 70% rule: If 8,400 of the last 12,000 blocks are version 4 or
greater, reject invalid version 4 blocks. (testnet4: 501 of last 1000)
* 80% rule ("Point of no return"): If 9,600 of the last 12,000 blocks
are version 4 or greater, reject all version <= 3 blocks. (testnet4: 750
of last 1000)
* Block version number is calculated after masking out high 16 bits
(final bit count TBD by versionBits outcome).
Jeff Garzik via bitcoin-dev ę¼ 2015-09-02 23:33 åÆ«å°:
> BIP 100 initial public draft:
> https://github.com/jgarzik/bip100/blob/master/bip-0100.mediawiki [1]
>
> Emphasis on "initial" This is a starting point for the usual open
> source feedback/iteration cycle, not an endpoint that Must Be This
> Way.
>
>
>
> Links:
> ------
> [1] https://github.com/jgarzik/bip100/blob/master/bip-0100.mediawiki
>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev at lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
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