Re: [dpdk-dev] free a memzone

[Mahdi Dashtbozorgi <mdasht@gmail.com>]

Hi Konstantin,

Thank you for your response.
Your Idea seems great! I will implement it this way.

Best Regards,
Mahdi.



On Mon, Jul 28, 2014 at 9:39 PM, Ananyev, Konstantin <
konstantin.ananyev@intel.com> wrote:

> Hi Mahdi,
>
> >Hi Konstantin,
> >Thank you very much. Your solution fixed my problem.
> >Is there a solution like this for resetting the memory zone, which is
> used by rte_malloc function?
> >Because if I use rte_malloc instead of malloc, in the case of application
> crash, the memory zone, which was used by rte_malloc in the previous run
> would be >unusable for the next run of slave process.
>
> Without significant modification inside librte_eal and/or librte_malloc -
> nothing comes on top of my head.
> If that is such a big problem to you, might be it is possible to change
> your whole process model a bit:
>
> In the parent process:
> - allocate memory/init run-time strcutures
> L1:
> - fork();
> - wait till child terminates
> - if it terminated abnormally, then free memory/re-init run-time
> structures.
> Goto L1
>
> Do actual packet processing inside child process.
>
> Would that help somehow?
> Konstantin
>
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Mahdi Dashtbozorgi
> > Sent: Thursday, July 24, 2014 6:20 AM
> > To: dev@dpdk.org
> > Subject: Re: [dpdk-dev] free a memzone
> >
> > Hi Bruce,
> >
> > Thank you for the response. That's a great Idea!
> > But I do not understand the last four parameters of this function.
> (vaddr,
> > paddr, pg_num, pg_shift)
> > I guess vaddr is the virtual address of the previously allocated mempool,
> yes
>
> > paddr is calculated using function call rte_mem_virt2phy(vaddr), am I
> > right?
> yes
>
>  >what about pg_num and pg_shift? how can I pass them correctly?
> From rte_mempool.h:
> "* @param pg_num
>  *   Number of elements in the paddr array.
>  * @param pg_shift
>  *   LOG2 of the physical pages size."
>
> If you are using memzone as externally allocated memory - it will be
> already physically continuos.
> So in your case pg_num = MEMPOOL_PG_NUM_DEFAULT,  pg_shift =
> MEMPOOL_PG_SHIFT_MAX.
>
> Though, I don't think rte_mempool_xmem_create() will help you in any way.
> Again from rte_mempool.h:
> "* Creates a new mempool named *name* in memory.
>  *
>  * This function uses ``memzone_reserve()`` to allocate memory. The
>  * pool contains n elements of elt_size. Its size is set to n.
>  * Depending on the input parameters, mempool elements can be either
> allocated
>  * together with the mempool header, or an externally provided memory
> buffer
>  * could be used to store mempool objects. In later case, that external
>  * memory buffer can consist of set of disjoint phyiscal pages."
>
> So xmem_create would still create a new ring, reserve a new memzone of
> mempool's metadata, etc.
> The only difference - it can use externally allocated memory to store
> mempool elements.
>
> As I understand what you need is sort of mempool_reset(): a function that
> would re-init mempool to just created state
> (all elements are free, lcores caches are empty, etc).
> Right now we don't have such function,  but I suppose something like that
> should do
> (note that I didn't run or even build it):
>
> If ((mp = rte_mempool_lookup(name)) != NULL {
>
> char ring_name[RTE_RING_NAMESIZE];
>
> /* save mp ring name. */
> memcpy(ring_name, mp->ring->name, sizeof ring_name);
>
> /* reset the ring. */
>   rte_ring_init(mp->ring, ring_name,  rte_align32pow2(mp->size+1),
> mp->ring->flags);
>
> /*repopulate mempool and reinit all its elements. */
> mempool_populate(mp, mp->size, 1, rte_pktmbuf_init, NULL);
>
> /* reset all lcore caches. */
>  memset(mp->local_cache, 0, sizeof(local_cahce));
>
>   /* reset statistics if needed. */
> } else {
>   /* create new mempool. */
> }
>
> Ideally such function should be in the librte_mempool of course, but if
> you are in a hurry - you probably can give it a try.
>
> Note that I assume that no other process, except failed/restarting
> secondary are using this mempool.
> If primary or some other secondary do, then first you need to stop them
> using this mempool and wait till they finish all their packet processing
> activity.
>
> Konstantin
>
> > Best Regards,
> > Mahdi.
> >
> >
> > On Thu, Jul 24, 2014 at 9:48 AM, Mahdi Dashtbozorgi <mdasht@gmail.com>
> > wrote:
> >
> > > Hi Bruce,
> > >
> > > Thank you for the response. That's a great Idea!
> > > But I do not understand the last four parameters of this function.
> (vaddr,
> > > paddr, pg_num, pg_shift)
> > > I guess vaddr is the virtual address of the previously allocated
> mempool,
> > > paddr is calculated using function call rte_mem_virt2phy(vaddr), am I
> > > right? what about pg_num and pg_shift? how can I pass them correctly?
> > >
> > > Best Regards,
> > > Mahdi.
> > >
> > >
> > > On Wed, Jul 23, 2014 at 11:09 PM, Richardson, Bruce <
> > > bruce.richardson@intel.com> wrote:
> > >
> > >> Rather than freeing the previously allocated memzone, could you not
> just
> > >> re-initialize the mempool using something like
> rte_mempool_xmem_create?
> > >>
> > >> > -----Original Message-----
> > >> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Mahdi
> Dashtbozorgi
> > >> > Sent: Wednesday, July 23, 2014 2:05 AM
> > >> > To: dev@dpdk.org
> > >> > Subject: Re: [dpdk-dev] free a memzone
> > >> >
> > >> > Hi guys,
> > >> >
> > >> > Is there any suggestion to free the previously allocated memzone?
> > >> > I really need help in this issue.
> > >> > Any help is appreciated.
> > >> >
> > >> > Best Regards,
> > >> > Mahdi.
> > >> >
> > >> >
> > >> >
> > >> > On Tue, Jul 22, 2014 at 4:03 PM, Mahdi Dashtbozorgi <
> mdasht@gmail.com>
> > >> > wrote:
> > >> >
> > >> > > Hi,
> > >> > >
> > >> > > I have two processes, which uses DPDK multi-process feature to
> > >> communicate.
> > >> > > Master process captures packets from NIC and put them to a ring
> > >> buffer,
> > >> > > which is shared between master and slave process.
> > >> > > The slave process looks up the shared ring buffer using
> > >> rte_ring_lookup
> > >> > > function and reads the packets.
> > >> > > The slave process needs a memory pool, too. Therefore, it creates
> a
> > >> > > mempool using rte_mempool_create. But If the slave process crashes
> > >> during
> > >> > > its processing and runs again, rte_mempool_create function fails
> and
> > >> tells
> > >> > > that there is a memory zone with that name.
> > >> > > If I use rte_mempool_lookup in this case, the memory pool is not a
> > >> clean
> > >> > > memory pool. Because the previous run of slave process did not
> > >> terminate
> > >> > > gracefully and did not return all the objects to the pool.
> > >> > > Is there any function to free an existing memory zone, which I
> call
> > >> before
> > >> > > rte_mempool_create to ensure that previous memory pool does not
> exists
> > >> > > anymore?
> > >> > >
> > >> > > Best Regards,
> > >> > > Mahdi.
> > >> > >
> > >>
> > >
> > >
>
>