More embarrassing microbenchmars for D's GC.
Leandro Lucarella
llucax at gmail.com
Tue Jun 10 07:40:19 PDT 2008
Walter Bright, el 9 de junio a las 17:12 me escribiste:
> Leandro Lucarella wrote:
> >But there are a few other results I can't explain:
> >1) Why is D gc (disabled or not) version ~25% slower than the D version
> > that uses malloc when iterating the list? It shouldn't be any GC
> > activity in that part. Could be some GC locallity issue that yields
> > more cache misses?
>
> There are so many factors that can influence this, it's hard to say without
> spending a lot of time carefully examining it.
But there is no GC activity there right?
> >2) Why is D malloc version ~33% slower than the C version? I took a look
> > at the generated assembly and it's almost identical:
> > <_Dmain+198>: lea -0x20(%ebp),%eax
> > <_Dmain+201>: lea 0x0(%esi,%eiz,1),%esi
> > <_Dmain+208>: addl $0x1,0x8(%eax)
> > <_Dmain+212>: adcl $0x0,0xc(%eax)
> > <_Dmain+216>: mov (%eax),%eax
> > <_Dmain+218>: test %eax,%eax
> > <_Dmain+220>: jne 0x804a240 <_Dmain+208>
> > <main+248>: lea -0x1c(%ebp),%eax
> > <main+251>: nop
> > <main+252>: lea 0x0(%esi,%eiz,1),%esi
> > <main+256>: addl $0x1,0x4(%eax)
> > <main+260>: adcl $0x0,0x8(%eax)
> > <main+264>: mov (%eax),%eax
> > <main+266>: test %eax,%eax
> > <main+268>: jne 0x8048550 <main+256>
> > <main+270>: movl $0x0,0x4(%esp)
> > <main+278>: movl $0x8049800,(%esp)
> >Tests attached.
>
> Without running a profiler, there's no way to be sure about just where in the
> code the time is being consumed.
Attached is the output of the gprof program (for the list-test-d-gc with
the GC running). I don't see any helpful information for the point 2), but
it shows clearly that most of the time is spent in garbage collection.
--
Leandro Lucarella (luca) | Blog colectivo: http://www.mazziblog.com.ar/blog/
----------------------------------------------------------------------------
GPG Key: 5F5A8D05 (F8CD F9A7 BF00 5431 4145 104C 949E BFB6 5F5A 8D05)
----------------------------------------------------------------------------
Si pensas que el alma no se ve
el alma sí se ve en los ojos
-------------- next part --------------
Flat profile:
Each sample counts as 0.01 seconds.
% cumulative self self total
time seconds seconds calls Ts/call Ts/call name
66.67 0.06 0.06 _D3gcx3Gcx11fullcollectMFPvZk
11.11 0.07 0.01 _D3gcx3Gcx4markMFPvPvZv
11.11 0.08 0.01 _D3gcx3Gcx9allocPageMFhZi
11.11 0.09 0.01 _D6gcbits6GCBits3setMFkZv
0.00 0.09 0.00 1 0.00 0.00 _D4test9__modinitFZv
0.00 0.09 0.00 1 0.00 0.00 _Dmain
% the percentage of the total running time of the
time program used by this function.
cumulative a running sum of the number of seconds accounted
seconds for by this function and those listed above it.
self the number of seconds accounted for by this
seconds function alone. This is the major sort for this
listing.
calls the number of times this function was invoked, if
this function is profiled, else blank.
self the average number of milliseconds spent in this
ms/call function per call, if this function is profiled,
else blank.
total the average number of milliseconds spent in this
ms/call function and its descendents per call, if this
function is profiled, else blank.
name the name of the function. This is the minor sort
for this listing. The index shows the location of
the function in the gprof listing. If the index is
in parenthesis it shows where it would appear in
the gprof listing if it were to be printed.
Call graph (explanation follows)
granularity: each sample hit covers 2 byte(s) for 11.11% of 0.09 seconds
index % time self children called name
<spontaneous>
[1] 66.7 0.06 0.00 _D3gcx3Gcx11fullcollectMFPvZk [1]
-----------------------------------------------
<spontaneous>
[2] 11.1 0.01 0.00 _D3gcx3Gcx4markMFPvPvZv [2]
-----------------------------------------------
<spontaneous>
[3] 11.1 0.01 0.00 _D3gcx3Gcx9allocPageMFhZi [3]
-----------------------------------------------
<spontaneous>
[4] 11.1 0.01 0.00 _D6gcbits6GCBits3setMFkZv [4]
-----------------------------------------------
0.00 0.00 1/1 __do_global_ctors_aux [859]
[22] 0.0 0.00 0.00 1 _D4test9__modinitFZv [22]
-----------------------------------------------
0.00 0.00 1/1 _D9dgccmain211_d_run_mainUiPPaPUAAaZiZi2goMFZv [854]
[23] 0.0 0.00 0.00 1 _Dmain [23]
-----------------------------------------------
This table describes the call tree of the program, and was sorted by
the total amount of time spent in each function and its children.
Each entry in this table consists of several lines. The line with the
index number at the left hand margin lists the current function.
The lines above it list the functions that called this function,
and the lines below it list the functions this one called.
This line lists:
index A unique number given to each element of the table.
Index numbers are sorted numerically.
The index number is printed next to every function name so
it is easier to look up where the function in the table.
% time This is the percentage of the `total' time that was spent
in this function and its children. Note that due to
different viewpoints, functions excluded by options, etc,
these numbers will NOT add up to 100%.
self This is the total amount of time spent in this function.
children This is the total amount of time propagated into this
function by its children.
called This is the number of times the function was called.
If the function called itself recursively, the number
only includes non-recursive calls, and is followed by
a `+' and the number of recursive calls.
name The name of the current function. The index number is
printed after it. If the function is a member of a
cycle, the cycle number is printed between the
function's name and the index number.
For the function's parents, the fields have the following meanings:
self This is the amount of time that was propagated directly
from the function into this parent.
children This is the amount of time that was propagated from
the function's children into this parent.
called This is the number of times this parent called the
function `/' the total number of times the function
was called. Recursive calls to the function are not
included in the number after the `/'.
name This is the name of the parent. The parent's index
number is printed after it. If the parent is a
member of a cycle, the cycle number is printed between
the name and the index number.
If the parents of the function cannot be determined, the word
`<spontaneous>' is printed in the `name' field, and all the other
fields are blank.
For the function's children, the fields have the following meanings:
self This is the amount of time that was propagated directly
from the child into the function.
children This is the amount of time that was propagated from the
child's children to the function.
called This is the number of times the function called
this child `/' the total number of times the child
was called. Recursive calls by the child are not
listed in the number after the `/'.
name This is the name of the child. The child's index
number is printed after it. If the child is a
member of a cycle, the cycle number is printed
between the name and the index number.
If there are any cycles (circles) in the call graph, there is an
entry for the cycle-as-a-whole. This entry shows who called the
cycle (as parents) and the members of the cycle (as children.)
The `+' recursive calls entry shows the number of function calls that
were internal to the cycle, and the calls entry for each member shows,
for that member, how many times it was called from other members of
the cycle.
Index by function name
[1] _D3gcx3Gcx11fullcollectMFPvZk [3] _D3gcx3Gcx9allocPageMFhZi [4] _D6gcbits6GCBits3setMFkZv
[2] _D3gcx3Gcx4markMFPvPvZv [22] _D4test9__modinitFZv [23] _Dmain
More information about the Digitalmars-d
mailing list