Re: [dpdk-dev] using hash table in a MP environment

[Venkat Thummala <venkat.thummala.1978@gmail.com>]

Hi Shirley,

Please refer the section 20.3 [Multi-Process Limitations] in DPDK
Programmers Guide.

The use of function pointers between multiple processes running based of
different
compiled binaries is not supported, since the location of a given function
in one
process may be different to its location in a second. This prevents the
librte_hash library from behaving properly as in a multi-threaded instance,
since it uses a pointer to the hash function internally.
To work around this issue, it is recommended that multi-process applications
perform the hash calculations by directly calling the hashing function from
the code
and then using the rte_hash_add_with_hash()/
rte_hash_lookup_with_hash() functions instead of the functions which do the
hashing internally, such as rte_hash_add()/rte_hash_lookup()

Thanks
Venkat


On 10 June 2014 17:05, Neil Horman <nhorman@tuxdriver.com> wrote:

> On Tue, Jun 10, 2014 at 11:02:03AM +0300, Uri Sidler wrote:
> > Hi,
> > I am currently using a hash table in a multi-process environment.
> > the master process creates the hash table which is later used by other
> > secondary processes.
> > but the secondary processes fail to use the hash table since the hash
> > function address actually points to a different fucntion. (this makes
> sense
> > since the address of the hash function is in fact different per process).
> > How can I solve this issue?
> >
> > Thanks,
> > Shirley.
> >
>
> Use shared memory.  see shmget
>
> Neil
>
>