Re: no hugepage with UIO poll-mode driver

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

2015-11-25 12:02, Bruce Richardson:
> On Wed, Nov 25, 2015 at 12:03:05PM +0100, Thomas Monjalon wrote:
> > 2015-11-25 11:00, Bruce Richardson:
> > > On Wed, Nov 25, 2015 at 11:23:57AM +0100, Thomas Monjalon wrote:
> > > > 2015-11-25 10:08, Bruce Richardson:
> > > > > On Wed, Nov 25, 2015 at 03:39:17PM +0900, Younghwan Go wrote:
> > > > > > Hi Jianfeng,
> > > > > > 
> > > > > > Thanks for the email. rte mempool was successfully created without any
> > > > > > error. Now the next problem is that rte_eth_rx_burst() is always returning 0
> > > > > > as if there was no packet to receive... Do you have any suggestion on what
> > > > > > might be causing this issue? In the meantime, I will be digging through
> > > > > > ixgbe driver code to see what's going on.
> > > > > > 
> > > > > > Thank you,
> > > > > > Younghwan
> > > > > > 
> > > > > 
> > > > > The problem is that with --no-huge we don't have the physical address of the memory
> > > > > to write to the network card. That's what it's marked as for testing only.
> > > > 
> > > > Even with rte_mem_virt2phy() + rte_mem_lock_page() ?
> > > > 
> > > With no-huge, we just set up a single memory segment at startup and set its
> > > "physaddr" to be the virtual address.
> > > 
> > >         /* hugetlbfs can be disabled */
> > >         if (internal_config.no_hugetlbfs) {
> > >                 addr = mmap(NULL, internal_config.memory, PROT_READ | PROT_WRITE,
> > >                                 MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
> > >                 if (addr == MAP_FAILED) {
> > >                         RTE_LOG(ERR, EAL, "%s: mmap() failed: %s\n", __func__,
> > >                                         strerror(errno));
> > >                         return -1;
> > >                 }
> > >                 mcfg->memseg[0].phys_addr = (phys_addr_t)(uintptr_t)addr;
> > 
> > rte_mem_virt2phy() does not use memseg.phys_addr but /proc/self/pagemap:
> > 
> >     /*
> >      * the pfn (page frame number) are bits 0-54 (see
> >      * pagemap.txt in linux Documentation)
> >      */
> >     physaddr = ((page & 0x7fffffffffffffULL) * page_size)
> >         + ((unsigned long)virtaddr % page_size);
> >
> 
> Yes, you are right. I was not aware that that function was used as part of the
> mempool init, but now I see that "rte_mempool_virt2phy()" does indeed call that
> function if hugepages are disabled, so my bad.

Do you think we could move --no-huge in the main section (not only for testing)?