[MassifVisualizer] Re: (no subject)

[Milian Wolff]

Yann Thierry-Mieg, 16.11.2010:
> Thanks for building this tool, it does sort of crash sometimes, but I
> installed without difficulty on my Mandriva.
> Nice tool on top of the excellent/great/[insert your own favorite
> superlative here] valgrind.
> Massif has much fewer gui than most tools in the suite (e.g.
> kcachegrind...).

Hey there, thanks for the kind words. But I don't know of any crashes, so 
please report it and make sure to attach the massif data file if possible:

https://bugs.kde.org/enter_bug.cgi?product=massif-visualizer&format=guided

> BTW, anybody know how to interpret the "extra-heap" column ?
> I get almost 30% of my memory locked up as "extra-heap". :/
> This doesn't look like management bytes (1 per bloc), and unless ALL my
> allocation are 5 bytes padded to 8 I don't see how 30% waste is possible.

From the valgrind manual:

#
The number of extra heap bytes allocated at that point. This reflects the 
number of bytes allocated in excess of what the program asked for. There are 
two sources of extra heap bytes.

First, every heap block has administrative bytes associated with it. The exact 
number of administrative bytes depends on the details of the allocator. By 
default Massif assumes 8 bytes per block, as can be seen from the example, but 
this number can be changed via the --heap-admin option.

Second, allocators often round up the number of bytes asked for to a larger 
number, usually 8 or 16. This is required to ensure that elements within the 
block are suitably aligned. If N bytes are asked for, Massif rounds N up to 
the nearest multiple of the value specified by the --alignment option.
#

see http://valgrind.org/docs/manual/ms-manual.html#ms-
manual.thesnapshotdetails

Also, such questions should probably go to
valgrind-users at lists.sourceforge.net

Bye
-- 
Milian Wolff
mail at milianw.de
http://milianw.de
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