Re: [Valgrind-users] measuring stack usage

[Dirk S. <val...@ds...>]

On Mon, 31 Mar 2008, bar...@gm... wrote:

>> Are the stats correct? I get below 20KB stack usage, but the tool crashs
>> for sure, when I set the stack to 32KB. 64KB works. Are there any
>> operating system or pthread overheads, which are not counted?
>
> The exp-drd algorithm runs on the stack of the client threads, so when 
> running a program under exp-drd (or any other Valgrind tool), more stack 
> space is needed than when a program is run natively. I was not aware 
> that exp-drd crashes when it runs out of stack space -- this it not very 
> elegant.

No, the program crashs outside of valgrind. It SEGFAULTS somewhere, when I 
reduce the thread stack to 32KB. Thought I was not able to debug, where it 
crashs (actually I also do not have the time to find it out). I will do 
some more testing. Maybe there are code paths, which I did not check with 
the exp-drd runs.

>> BTW: Could you update drd_print_usage() ? Many options and the defaults
>> are missing :-) And the Docs still state rwlocks are not supported, but
>> you have --trace-rwlock as option. Are rwlocks supported? I get lots
>> of "Conflicting load by thread 1/1". Could you add some little notes to
>> the docs, how to interpret the output? I could not follow it. The first
>> Statement and the first "Other segment start" matched, but the following
>> ones point to totally different structures.
>
> Regarding reader-writer locks: I did not yet have the time to test 
> reader-writer lock support in exp-drd thoroughly, so it is possible that 
> the implementation of reader-writer locks in exp-drd is not yet correct. 
> If you have a small sample program for which you think exp-drd's output 
> is incorrect, you are welcome to post it to the valgrind-users mailing 
> list.

I will see. Actually at the moment I only have a medium sized closed 
source program I want to check. It is a server tool which works fine, but 
surely has some hidden problems.

Ciao
-- 
http://www.dstoecker.eu/ (PGP key available)