* Use a bit less code to calculate hashfull(). Change post increment to preincrement as is more standard
in the rest of stockfish. Scale result so we report 100% instead of 99.9% when completely full.
No functional change.
As noticed in the forum, a crash in extract_ponder_from_tt could result
if hash size is set before the ponder move is printed. While it is arguably
a GUI issue (but it got me on the cli), it is easy to avoid this issue.
Closes https://github.com/official-stockfish/Stockfish/pull/1856
No functional change.
The patch was tested for correctness by running bench with and
without the change against current master, and the tablebase hit
numbers were found to be identical in both cases. See the pull
request comments for details:
https://github.com/official-stockfish/Stockfish/pull/1826
No functional change.
Preparation commit for the upcoming Stockfish 10 version, giving a chance to catch last minute feature bugs and evaluation regression during the one-week code freeze period. Also changing the copyright dates to include 2019.
No functional change
Enable numa machinery only for STRICTLY MORE than 8 threads. Reason for this
change is that nowadays SMP tests are always done with 8 threads. That is a
problem for multi-socket Windows machines running on fishtest.
No functional change
Storing unconditionally the current generation and bound is equivalent to master.
Part of the condition was added as a speed optimization in #429.
Here the branch is fully eliminated.
passed STC single-threaded:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 73515 W: 16378 L: 16359 D: 40778
http://tests.stockfishchess.org/tests/view/5b2fc38c0ebc5902b2e57fd5
passed STC multi-threaded:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 63725 W: 12916 L: 12874 D: 37935
http://tests.stockfishchess.org/tests/view/5b307b8f0ebc5902b2e5895f
The multithreaded test was run after a plausible suggestion by @mstembera that the effect of this could be larger with many cores. The result seems to indicate this doesn't really matter on the 8core architecture abundantly available on fishtest.
No functional change
Makes sure the potential benefit of first touch does not depend on
the order of the UCI commands Threads and Hash, by reallocating the
hash if a Threads is issued. The cost is zeroing the TT once more
than needed. In case the prefered order (first Threads than Hash)
is employed, this amounts to zeroing the default sized TT (16Mb),
which is essentially instantaneous.
Follow up for https://github.com/official-stockfish/Stockfish/pull/1601
where additional data and discussion is available.
Closes https://github.com/official-stockfish/Stockfish/pull/1620
No functional change.
Stockfish currently takes a while to clear the TT when using larger hash sizes.
On one machine with 128 GB hash it takes about 50 seconds with a single thread,
allowing it to use all allocated cores brought that time down to 4 seconds on
some Linux systems. The patch was further tested on Windows and refined with
NUMA binding of the hash initializing threads (we refer to pull request #1601
for the complete discussion and the speed measurements).
Closes https://github.com/official-stockfish/Stockfish/pull/1601
No functional change
as discussed in issue #1349, the way pages are allocated with calloc might imply some overhead on first write.
This overhead can be large and slow down the first search after a TT resize significantly, especially for large TT.
Using an explicit clear of the TT on resize fixes this problem.
Not implemented, but possibly useful for large TT, is to do this zero-ing using all search threads. Not only would this be faster, it could also lead to a more favorable memory allocation on numa systems with a first touch policy.
No functional change.
For efficiency reasons current master only allows for transposition table sizes that are N = 2^k in size, the index computation can be done efficiently as (hash % N) can be written instead as (hash & 2^k - 1). On a typical computer (with 4, 8... etc Gb of RAM), this implies roughly half the RAM is left unused in analysis.
This issue was mentioned on fishcooking by Mindbreaker:
http://tests.stockfishchess.org/tests/view/5a3587de0ebc590ccbb8be04
Recently a neat trick was proposed to map a hash into the range [0,N[ more efficiently than (hash % N) for general N, nearly as efficiently as (hash % 2^k):
https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/
namely computing (hash * N / 2^32) for 32 bit hashes. This patch implements this trick and now allows for general hash sizes. Note that for N = 2^k this just amounts to using a different subset of bits from the hash. Master will use the lower k bits, this trick will use the upper k bits (of the 32 bit hash).
There is no slowdown as measured with [-3, 1] test:
http://tests.stockfishchess.org/tests/view/5a3587de0ebc590ccbb8be04
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 128498 W: 23332 L: 23395 D: 81771
There are two (smaller) caveats:
1) the patch is implemented for a 32 bit hash (so that a 64 bit multiply can be used), this effectively limits the number of clusters that can be used to 2^32 or to 128Gb of transpostion table. That's a change in the maximum allowed TT size, which could bother those using 256Gb or more regularly.
2) Already in master, an excluded move is hashed into the position key in rather simple way, essentially only affecting the lower 16 bits of the key. This is OK in master, since bits 0-15 end up in the index, but not in the new scheme, which picks the higher bits. This is 'fixed' by shifting the excluded move a few bits up. Eventually a better hashing scheme seems wise.
Despite these two caveats, I think this is a nice improvement in usability.
Bench: 5346341
Rename shift_bb() to shift(), and DELTA_S to SOUTH, etc.
to improve code readability, especially in evaluate.cpp
when they are used together:
old b = shift_bb<DELTA_S>(pos.pieces(PAWN))
new b = shift<SOUTH>(pos.pieces(PAWN))
While there fix some small code style issues.
No functional change.
This non-functional change patch is a deep work to allow SF to be independent
from the actual value of ONE_PLY (currently set to 1). I have verified SF is
now independent for ONE_PLY values 1, 2, 4, 8, 16, 32 and 256.
This patch gives consistency to search code and enables future work, opening
the door to safely tweaking the ONE_PLY value for any reason.
Verified for no speed regression at STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 95643 W: 17728 L: 17737 D: 60178
No functional change.
Only refresh TT entry when it's really necessary.
This should give a small speed boost for some machines.
And it's a risk-free change.
No functional change.
Resolves#429
This is an old patch from Jean-Francois Romang to send
UCI hashfull info to the GUI:
https://github.com/mcostalba/Stockfish/pull/60/files
It was wrongly judged as a slowdown, but it takes much
less than 1 ms to run, indeed on my core i5 2.6Ghz it
takes about 2 microsecs to run!
Regression test is good:
STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 7352 W: 1548 L: 1401 D: 4403
LTC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 61432 W: 10307 L: 10251 D: 40874
I have set the name of the author to the original
one.
No functional change.
On platforms where size_t is 32 bit, we
can have an overflow in this expression:
(mbSize * 1024 * 1024)
Fix it setting max hash size of 2GB on platforms
where size_t is 32 bit.
A small rename while there: now struct Cluster
is definied inside class TranspositionTable so
we should drop the redundant TT prefix.
No functional change.
It is up to material (and pawn) table look up
code to know where the per-thread tables are,
so change API to reflect this.
Also some comment fixing while there
No functional change.
In particular seems more natural to return
bool and TTEntry on the same line, actually
we should pass and return them as a pair,
but due to limitations of C++ and not wanting
to use std::pair this can be an acceptable
compromise.
No functional change.
Resolves#157
TCEC season 3, which is due to start in a few weeks, just
had its server upgraded to 64GB RAM and will therefore allow
16GB hash to be used per engine.
This is almost the upper limit without changing the
type of size and hashMask. After this we need to
move to uint64_t instead of uint32_t.
No functional change.
1/ eval margin and gains removed:
16bit are now free on TT entries, due to the removal of eval margin. may be useful
in the future :) gains removed: use instead by Value(128). search() and qsearch()
are now consistent in this regard.
2/ futility_margin()
linear formula instead of complex (log(depth), movecount) formula.
3/ unify pre & post futility pruning
pre futility pruning used depth < 7 plies, while post futility pruning used
depth < 4 plies. Now it's always depth < 7.
Tested with fixed number of games both at short TC:
ELO: 0.82 +-2.1 (95%) LOS: 77.3%
Total: 40000 W: 7939 L: 7845 D: 24216
And long TC
ELO: 0.59 +-2.0 (95%) LOS: 71.9%
Total: 40000 W: 6876 L: 6808 D: 26316
bench 7243575
