New pure-python CPU miner, for fun and testing - page 3.

kseistrup

hero member

Activity: 566

Merit: 500

Unselfish actions pay back better

The way I see it, these two lines have the effect of reversing the entire data string:

Code:

hash = bufreverse(hash)
hash = wordreverse(hash)

and could be replaced by

Code:

hash = hash[::-1]

If I am right, then the following small patch will triple the efficiency (from ~32 khash/sec to more than 100 khash/sec):

Code:

--- pyminer.py 2011-02-17 19:37:34.254845344 +0100
+++ pyminer-opt.py 2011-02-17 19:47:44.794843788 +0100
@@ -76,18 +76,10 @@
def getwork(self, data=None):
return self.rpc('getwork', data)

-def uint32(x):
- return x & 0xffffffffL
-
-def bytereverse(x):
- return uint32(( ((x) << 24) | (((x) << 8) & 0x00ff0000) |
- (((x) >> 8) & 0x0000ff00) | ((x) >> 24) ))
-
def bufreverse(in_buf):
out_words = []
for i in range(0, len(in_buf), 4):
- word = struct.unpack('@I', in_buf[i:i+4])[0]
- out_words.append(struct.pack('@I', bytereverse(word)))
+ out_words.append(in_buf[i:i+4][::-1])
return ''.join(out_words)

def wordreverse(in_buf):
@@ -115,10 +107,7 @@

hash_o = hashlib.sha256()
hash_o.update(hash1)
- hash = hash_o.digest()
-
- hash = bufreverse(hash)
- hash = wordreverse(hash)
+ hash = hash_o.digest()[::-1]

hash_str = hash.encode('hex')
l = long(hash_str, 16)

A few other optimizations can be made within the loop to raise the efficiency to approx. 110 khash/sec on my machine, but this will make the code less legible and is probably not worth it.

Cheers,

jgarzik

legendary

Activity: 1596

Merit: 1100

Quote from: kseistrup on February 17, 2011, 07:41:40 AM

Quote from: jgarzik on February 16, 2011, 05:57:19 PM

http://yyz.us/bitcoin/pyminer.py

It is computational expensive to repeatedly concatenate strings in Python. I suggest using [].append() in the bufreverse() and wordreverse() methods:

Updated the source code with your suggestions. Thanks -- this is my second python program, so I guarantee there are other improvements that expert Python programmers can discover.

kseistrup

hero member

Activity: 566

Merit: 500

Unselfish actions pay back better

Quote from: epicenter on February 17, 2011, 08:08:46 AM

required args?
not sure of the format for files in python

Pyminer takes as its single argument the name of the config file.

The config file consists of lines of the form

Code:

key = value

Keys can be host, port, rpcuser, rpcpass, threads, logdir and hashmeter.

Cheers,

epicenter

newbie

Activity: 10

Merit: 0

required args?
not sure of the format for files in python

kseistrup

hero member

Activity: 566

Merit: 500

Unselfish actions pay back better

Furthermore, you could bytereverse a 4-byte buf using it's own builtin medthod:

Code:

>>> x = 'abcd'
>>> x[::-1]
'dcba'
>>>

No need to use the pack/unpack stuff…

Cheers,

Cdecker

hero member

Activity: 489

Merit: 505

Great stuff, finally I can wrap my head around how mining works without having to crawl through additional stuff

kseistrup

hero member

Activity: 566

Merit: 500

Unselfish actions pay back better

Quote from: jgarzik on February 16, 2011, 05:57:19 PM

http://yyz.us/bitcoin/pyminer.py

It is computational expensive to repeatedly concatenate strings in Python. I suggest using [].append() in the bufreverse() and wordreverse() methods:

Code:

diff --git a/pyminer.py b/pyminer.py
index cfd79a2..f972a75 100644
--- a/pyminer.py
+++ b/pyminer.py
@@ -84,21 +84,18 @@ def bytereverse(x):
(((x) >> 8) & 0x0000ff00) | ((x) >> 24) ))

def bufreverse(in_buf):
- out_words = ""
+ out_words = []
for i in range(0, len(in_buf), 4):
word = struct.unpack('@I', in_buf[i:i+4])[0]
- out_words += struct.pack('@I', bytereverse(word))
- return out_words
+ out_words.append(struct.pack('@I', bytereverse(word)))
+ return ''.join(out_words)

def wordreverse(in_buf):
out_words = []
for i in range(0, len(in_buf), 4):
out_words.append(in_buf[i:i+4])
out_words.reverse()
- out_buf = ""
- for word in out_words:
- out_buf += word
- return out_buf
+ return ''.join(out_words)

class Miner:
def __init__(self, id):

Cheers,

Kiv

full member

Activity: 162

Merit: 100

This is really cool

It'll definitely help me understand better how the mining works.

kseistrup

hero member

Activity: 566

Merit: 500

Unselfish actions pay back better

Quote from: kseistrup on February 16, 2011, 06:31:28 PM

I wonder if this will run faster under PyPy?

I just had to try… Wink

Running pyminer on Python2.7 yields ~30 khash/sec, under PyPy less than 3 khash/sec. Oh, well…

Cheers,

kseistrup

hero member

Activity: 566

Merit: 500

Unselfish actions pay back better

Quote from: jgarzik on February 16, 2011, 05:57:19 PM

This is single-threaded, and pulls a whopping 43 Khash/sec on my box.

Cool!

I wonder if this will run faster under PyPy (pystone.main() is more than 10 times faster on PyPy on my machine)?

Cheers,

Cryptoman

hero member

Activity: 726

Merit: 500

Quote from: jgarzik on February 16, 2011, 05:57:19 PM

This is single-threaded, and pulls a whopping 43 Khash/sec on my box.

What type of system are you running? Hamsters in a box with pencil and paper? Grin

jgarzik

legendary

Activity: 1596

Merit: 1100

Here is a new high performance, highly optimized CPU miner:

https://github.com/jgarzik/pyminer

This pulls a whopping 256 Khash/sec per thread on my box.

The main purpose is to demonstrate the mining algorithm, in a small amount of portable code. And to have a bit of fun.

Topic: New pure-python CPU miner, for fun and testing - page 3. (Read 25622 times)