On Mon, Feb 7, 2011 at 9:28 AM, Konstantin Serebryany <
[email protected]> wrote:
>
> On Sun, Feb 6, 2011 at 10:14 PM, Bart Van Assche <[email protected]>wrote:
>
>> On Sat, Feb 5, 2011 at 5:54 PM, Konstantin Serebryany <
>> [email protected]> wrote:
>>
>>>
>>> On Sat, Feb 5, 2011 at 7:36 PM, Bart Van Assche <[email protected]>wrote:
>>>
>>>> On Sat, Feb 5, 2011 at 2:22 PM, Konstantin Serebryany <
>>>> [email protected]> wrote:
>>>>
>>>>> FYI
>>>>> ThreadSanitizer will not report anything on this test, even with
>>>>> --free-is-write (which is on by default) because this tool assumes the
>>>>> malloc implementation to be correct and ignores every access inside malloc
>>>>> and friends.
>>>>> I haven't seen any false positives due to --free-is-write (in
>>>>> ThreadSanitizer) over last ~6 months, but we found tons of real races with
>>>>> this flag. Just a fresh example:
>>>>> http://code.google.com/p/chromium/issues/detail?id=72042
>>>>>
>>>>
>>>> Hello Konstantin,
>>>>
>>>> Has that --free-is-write feature already been tested in combination with
>>>> custom memory allocators ?
>>>>
>>> What kind of custom memory allocators?
>>> We regularly run it with programs linked against tcmalloc.
>>>
>>
>> Hello Konstantin,
>>
>> With "custom memory allocators" I was referring to those using the
>> VG_USERREQ__MALLOCLIKE_BLOCK and VG_USERREQ__FREELIKE_BLOCK client requests
>> and not to those that replace malloc() like e.g. tcmalloc.
>>
>
> ThreadSanitizer does not support VG_USERREQ__FREELIKE_BLOCK -- never found
> a use for it yet.
> However if a program uses a lot of custom free lists it could be useful
> (and it will be trivial to implement).
>
Hello Konstantin,
Sure, I don't doubt that implementing support for VG_USERREQ__FREELIKE_BLOCK
in TS would be trivial to implement. What might be hard to implement
regarding --free-is-write is to ignore the memory accesses inside the custom
allocator. This is because such a custom allocator issues
VG_USERREQ__MALLOCLIKE_BLOCK after it has finished updating its internal
data structures and because the tool is not informed when the custom memory
allocator in the client starts updating its internal data structures.
Bart.
------------------------------------------------------------------------------
The modern datacenter depends on network connectivity to access resources
and provide services. The best practices for maximizing a physical server's
connectivity to a physical network are well understood - see how these
rules translate into the virtual world?
http://p.sf.net/sfu/oracle-sfdevnlfb
_______________________________________________
Valgrind-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/valgrind-users
