Re: [Gcl-devel] hash redux

[Camm Maguire]

Greetings!  Before we look further, let me run this in gdb.  I have
encountered situations in which the gprof profilier fails to detect the
end of certain (optimized, inlined) functions and misreports the
statistics.  More later when I get this done.

Matt, I was trying the same in ccl just to see where we stand, and could
not load the portcullis.  Do you happen to have a comparable ccl time
for this handy?

Take care,

Matt Kaufmann <address@hidden> writes:

> Hi, Jared and Camm --
>
> I ran the experiment you suggested, Jared (thanks for the suggestion).
> In books/centaur/gl/:
>
> (ubt! 1)
> (include-book "portcullis")
> (rebuild "solutions.lisp" t)
> (u)
> (time$ (def-gl-thm 1f
>   :hyp (and (unsigned-byte-p 3000 x)
>             (unsigned-byte-p 3000 y))
>   :concl (equal (+ x y) (+ y x))
>   :g-bindings (gl::auto-bindings (:mix (:nat x 3000)
>                                        (:nat y 3000)))))
>
> That took 78 seconds (a very nice improvement!).  Then:
>
> ACL2 !>:q
>
> Exiting the ACL2 read-eval-print loop.  To re-enter, execute (LP).
> ACL2>(hons-summary)
>
> Normed Objects Summary
>
>  - NIL-HT:                     4 count,           5,000 size ( 0.08% full)
>  - CDR-HT:             9,071,974 count,      12,974,622 size (69.92% full)
>  - CDR-HT-EQL:                 0 count,           1,000 size ( 0.00% full)
>  - STR-HT:                     1 count,           1,000 size ( 0.10% full)
>  - PERSIST-HT:                 0 count,             100 size ( 0.00% full)
>  - FAL-HT:                     0 count,           1,000 size ( 0.00% full)
>
> NIL
>
> ACL2>(hl-hspace-str-ht *default-hs*)
>
> #<hash-table 0000000004e06af0>
>
> ACL2>
>
> (I did some searching and did find another 'equal hash table besides
> that str-ht, namely; *hcomp-book-ht*, but it's quite small and not
> relevant here.)
>
> So I'm again stumped, since the cdr-ht is, I think, an 'eq hash
> table.
>
> Camm, is there a way to identify the callers that are setting a hash
> table with test 'equal?  The profile you sent seems to be at the level
> of C, so I don't know what to trace.
>
> -- Matt
>    From: "Jared C. Davis" <address@hidden>
>    Date: Mon, 11 Nov 2013 16:18:24 -0600
>    Cc: Camm Maguire <address@hidden>,
>          "address@hidden" <address@hidden>
>
>    Hi,
>
>    I believe Matt is correct that the only use of EQUAL hash tables in
>    the (h) part of ACL2(h) is for string hashing.  In fact, for the most
>    part, in a single-threaded context, I think there should typically be
>    just a single string hash table.
>
>    At the relevant part of your benchmark, you might run (hons-summary)
>    to see the size and count of this table, in case that's helpful.  Or
>    if you want to get your hands on the hash table to really take a deep
>    look at it, you can try, e.g.,:
>
>    ACL2 !>(hons "foo" "bar")
>    ("foo" . "bar")
>    ACL2 !>:q
>    :q
>
>    Exiting the ACL2 read-eval-print loop.  To re-enter, execute (LP).
>    ? (hl-hspace-str-ht *default-hs*)
>    #<HASH-TABLE :TEST EQUAL size 2/1000 #x30200EA5441D>
>
>    Cheers,
>    Jared
>
>    On Mon, Nov 11, 2013 at 3:21 PM, Matt Kaufmann <address@hidden> wrote:
>    > Hi, Camm --
>    >
>    > That's interesting, but I'm confused, and I'm definitely not an expert
>    > on hash tables.  I looked at the files that implement the "(h)" part
>    > of ACL2(h), which is almost certainly what is involving hash tables,
>    > and it looks to me like maybe the only 'equal hash tables are for
>    > strings.
>    >
>    > I'm forwarding this to Jared, since he is the most recent author of
>    > that code (plus, you mention him as helping with potentially related
>    > reader issues), in case he has time to shed light on this.
>    >
>    > -- Matt
>    >    From: Camm Maguire <address@hidden>
>    >    Date: Mon, 11 Nov 2013 12:49:41 -0500
>    >
>    >    Greetings!
>    >
>    >    Just a followup -- the remaining time appears to be in sethash for an
>    >    'equal hash-table:
>    >
>    >    
> =============================================================================
>    >    index % time    self  children    called     name
>    >                                 103979625             sethash [1]
>    >    [1]     84.2    2.11   49.03       0+103979625 sethash [1]
>    >                   22.58    6.16 167566772/167566772     fShash_equal [2]
>    >                    0.00   20.28  119656/131885      alloc_relblock [6]
>    >                    0.01    0.00  119656/205048      alloc_object [47]
>    >                                 103979625             sethash [1]
>    >    -----------------------------------------------
>    >                   22.58    6.16 167566772/167566772     sethash [1]
>    >    [2]     47.3   22.58    6.16 167566772         fShash_equal [2]
>    >                    5.25    0.00 363849475/363849475     hash_eql [12]
>    >                    0.91    0.00 1174935219/1174940911     eql1 [18]
>    >                    0.00    0.00      12/2577623     Fand <cycle 2> [151]
>    >    -----------------------------------------------
>    >                    0.29    5.78       3/14          make_cons [9]
>    >                    1.06   21.19      11/14          alloc_relblock [6]
>    >    [3]     46.6    1.35   26.97      14         GBC [3]
>    >                   26.93    0.00 25304834/25331171     sgc_mark_object1 
> <cycle 1> [5]
>    >    
> =============================================================================
>    >
>    >    This is somewhat remarkable, as the 'eql gethash calls which greatly
>    >    dominate in number are no longer on the radar.  Presumably the 
> algorithm
>    >    makes some complex cons, (definitely not your grandmother's '(1 2 3)
>    >    list), uses an 'equal hashtable to make it equal-unique, and then uses
>    >    that as a key in an 'eql hashtable for the real heavy work.
>    >
>    >    This just reminded me of the work we did earlier regarding the loading
>    >    of complex conses in compiled files, which overloaded the #= reader
>    >    until we memoized the routine calculating the hash-equal index.  This 
> is
>    >    barely necessary to the gcl compiler -- the point is to catch errors
>    >    where the constant list to be compiled in changes during compilation.
>    >    And as I indicated earlier, we flush the memoizing hash tables on each
>    >    compile-file.  This, together with the implementation of the 'hybrid' 
> #=
>    >    algorithm suggested by Jared, made the loading of these conses very
>    >    fast.
>    >
>    >    My question is if we've learned anything which might make the above
>    >    results yet faster.  By default, the hash-equal index descends no more
>    >    than three levels, car and cdr, into a cons to xor up the index.  It
>    >    does not attempt to descend the entire structure memoizing as one goes
>    >    like the compiler version.  There the depth limit is much greater 
> (1000)
>    >    due to its purpose and the absence of any table.  My intuition tells 
> me
>    >    that there is no way a memoized version of the generic hash-equal 
> would
>    >    pay off.  It seems we would have to flush on each call, or never.  It
>    >    would only speed up index calculations of great depth, which is only
>    >    useful in hash tables if your index is insufficiently random at the
>    >    default depth of 3.  This does not appear the case, as #'equal itself 
> is
>    >    absent from the profiling report, implying that the hit rate to the
>    >    index is good.
>    >
>    >    I suppose an 'equal hashtable could keep an 'eq hashtable internally 
> for
>    >    the life of the table.  That might be interesting.
>    >
>    >    In any case, I don't want to waste a lot of time reinventing some
>    >    wheel.  If you or any of the other hashtable experts have some wisdom
>    >    here, I'd be most appreciative.
>    >
>    >    Take care,
>    >    --
>    >    Camm Maguire                                        address@hidden
>    >    
> ==========================================================================
>    >    "The earth is but one country, and mankind its citizens."  --  
> Baha'u'llah
>    >
>    >
>    > _______________________________________________
>    > Gcl-devel mailing list
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>    > https://lists.gnu.org/mailman/listinfo/gcl-devel
>
>
>
>    -- 
>    Jared C. Davis <address@hidden>
>    11410 Windermere Meadows
>    Austin, TX 78759
>    http://www.cs.utexas.edu/users/jared/
>
>
>
>
>

-- 
Camm Maguire                                        address@hidden
==========================================================================
"The earth is but one country, and mankind its citizens."  --  Baha'u'llah