Re: [dpdk-dev] Api in dpdk to get total free physical memory

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 08-Mar-18 9:36 PM, Venumadhav Josyula wrote:
> Hi All,
> 
> 
> 
> Like ‘rte_eal_get_physmem_size’ api to the total size of the physical
> memory. Is there an API to get to get total free memory physical memory
> available ?
> 
> 
> 
> We want such API we are planning to implement such API for the same
> 
> 
> 
> /* get the total size of memory */
> 
> uint64_t
> 
> rte_eal_get_physmem_free(int socket_id)
> 
> {
> 
> const struct rte_mem_config *mcfg;
> 
> unsigned i = 0;
> 
> uint64_t total_len = 0;
> 
> 
> 
> /* get pointer to global configuration */
> 
> mcfg = rte_eal_get_configuration()->mem_config;
> 
> 
> 
> for (i=0; i<RTE_MAX_MEMSEG; i++) {
> 
> if (mcfg->free_memseg[i].addr == NULL)
> 
> break;
> 
> 
> 
> if (mcfg->free_memseg[i].len == 0)
> 
> continue;
> 
> 
> 
> /* bad socket ID */
> 
> if (socket_id != SOCKET_ID_ANY &&
> 
> mcfg->free_memseg[i].socket_id != SOCKET_ID_ANY &&
> 
> socket_id != mcfg->free_memseg[i].socket_id)
> 
> continue;
> 
> 
> 
> total_len += mcfg->free_memseg[i].len;
> 
> }
> 
> 
> 
> return total_len;
> 
> }
> 
> 
> 
> Thanks,
> 
> Regards
> 
> Venu
> 

All memory is registered on the heap, so you might want to look at heap 
stats to get the same information :) It would also arguably be more 
useful because just the size of memory will not tell you how much you 
can allocate, because memory may be heavily fragmented, and heap stats 
will also tell you biggest free memory block size.

Bear in mind, however, that there is work in progress [1] to enable 
mapping/unmapping hugepages at runtime, which would make such an API 
more or less useless - just because you don't have much free space *now* 
doesn't mean you can't allocate more :)

[1] http://dpdk.org/ml/archives/dev/2018-March/092070.html

-- 
Thanks,
Anatoly