Re: DPDK (and rte_*alloc family) friendly Valgrind

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2016-02-13 12:30, Luca Boccassi:
> On Thu, 2016-02-11 at 08:34 +0100, Thomas Monjalon wrote:
> > 2016-02-10 22:54, Luca Boccassi:
> >  I created a set of patches for Valgrind that add support for the
> > > rte_*alloc family of functions. We use it for memcheck (I added support
> > > for other all the other Valgrind tools like cachegrind as well, but it's
> > > less tested), and find it extremely useful, since the vanilla version
> > > cannot intercept and report leaks cause by rte_*alloc functions from
> > > librte_malloc.
> > 
> > Thank you Luca.
> > I think it deserves to be visible in the DPDK doc.
> > What about adding some explanations in
> > https://urldefense.proofpoint.com/v2/url?u=http-3A__dpdk.org_doc_guides_prog-5Fguide_profile-5Fapp.html&d=CwICAg&c=IL_XqQWOjubgfqINi2jTzg&r=QTEM8ICX7t_SLgWP3qPWtKiwKMps487LPWQx-B9AqIc&m=QXy2HY_6FCRpB2dqb0AfDLoTIJ2MpHaKS_Bd5WKYgMQ&s=d4OWq_1QIlrYTxkCHIsQqn7p0887PWo4RaYa7PZeeII&e= 
> > or
> > https://urldefense.proofpoint.com/v2/url?u=http-3A__dpdk.org_doc_guides_prog-5Fguide_env-5Fabstraction-5Flayer.html-23malloc&d=CwICAg&c=IL_XqQWOjubgfqINi2jTzg&r=QTEM8ICX7t_SLgWP3qPWtKiwKMps487LPWQx-B9AqIc&m=QXy2HY_6FCRpB2dqb0AfDLoTIJ2MpHaKS_Bd5WKYgMQ&s=J36uf3GxS8AuoM2eQje4VTbXuF4WLmxGKIXM3RslaOA&e= 
> > ?
> 
> Hi Thomas,
> 
> Thanks, anything I could help with for that to happen?

Yes, the documentation is in the git tree.
If you have time, it would be nice to send a patch on this list to
point your patches and explain how it works (below notes can be included).
The guide for doc contribution is http://dpdk.org/doc/guides/contributing/documentation.html

> Also, a few words about the actual implementation.
> 
> Valgrind re-implements the whole *alloc and friends internally. There is
> a common framework shared between the various tools, and each builds on
> top of it.
> 
> What I've done is to map the various rte_*alloc/free functions on top of
> Valgrind's implementation of posix_memalign/free. This was done in order
> to respect the cache alignment parameter of rte_malloc and friends. I've
> tested to make sure that this works correctly, as we rely heavily upon
> it.
> 
> I have not, however, implemented support for NUMA sockets. There is no
> such concept inside Valgrind's framework at the moment, so it would be a
> monumental task. The NUMA socket parameter will simply be ignored. I do
> not believe it would be very useful to implement support for it, as it
> doesn't add much. For the purpose of memory leaks detection, I don't
> think it matters much on which socket a memory block is allocated.
> 
> This might have an effect on cachegrind though, so it's worth noting and
> bearing it in mind when using cachegrind rather than memcheck.
> 
> I've added a note on Github.

Thanks