Re: [dpdk-dev] [PATCH v2] eal: change default per socket memory allocation

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

Hi Venky,

There were comments on the first version of this patch and you suggested to 
try this new implementation.
So do you acknowledge this patch?

Thanks for your review

2014-05-09 15:30, David Marchand:
> From: Didier Pallard <didier.pallard@6wind.com>
> 
> Currently, if there is more memory in hugepages than the amount
> requested by dpdk application, the memory is allocated by taking as much
> memory as possible from each socket, starting from first one.
> For example if a system is configured with 8 GB in 2 sockets (4 GB per
> socket), and dpdk is requesting only 4GB of memory, all memory will be
> taken in socket 0 (that have exactly 4GB of free hugepages) even if some
> cores are configured on socket 1, and there are free hugepages on socket
> 1...
> 
> Change this behaviour to allocate memory on all sockets where some cores
> are configured, spreading the memory amongst sockets using following
> ratio per socket:
> N° of cores configured on the socket / Total number of configured cores
> * requested memory
> 
> This algorithm is used when memory amount is specified globally using
> -m option. Per socket memory allocation can always be done using
> --socket-mem option.
> 
> Changes included in v2:
> - only update linux implementation as bsd looks not to be ready for numa
> - if new algorithm fails, then defaults to previous behaviour
> 
> Signed-off-by: Didier Pallard <didier.pallard@6wind.com>
> Signed-off-by: David Marchand <david.marchand@6wind.com>
> ---
>  lib/librte_eal/linuxapp/eal/eal_memory.c |   50
> +++++++++++++++++++++++++++--- 1 file changed, 45 insertions(+), 5
> deletions(-)
> 
> diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c
> b/lib/librte_eal/linuxapp/eal/eal_memory.c index 73a6394..471dcfd 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_memory.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
> @@ -881,13 +881,53 @@ calc_num_pages_per_socket(uint64_t * memory,
>  	if (num_hp_info == 0)
>  		return -1;
> 
> -	for (socket = 0; socket < RTE_MAX_NUMA_NODES && total_mem != 0; socket++)
> { -		/* if specific memory amounts per socket weren't requested */
> -		if (internal_config.force_sockets == 0) {
> +	/* if specific memory amounts per socket weren't requested */
> +	if (internal_config.force_sockets == 0) {
> +		int cpu_per_socket[RTE_MAX_NUMA_NODES];
> +		size_t default_size, total_size;
> +		unsigned lcore_id;
> +
> +		/* Compute number of cores per socket */
> +		memset(cpu_per_socket, 0, sizeof(cpu_per_socket));
> +		RTE_LCORE_FOREACH(lcore_id) {
> +			cpu_per_socket[rte_lcore_to_socket_id(lcore_id)]++;
> +		}
> +
> +		/*
> +		 * Automatically spread requested memory amongst detected sockets
> according +		 * to number of cores from cpu mask present on each socket
> +		 */
> +		total_size = internal_config.memory;
> +		for (socket = 0; socket < RTE_MAX_NUMA_NODES && total_size != 0;
> socket++) { +
> +			/* Set memory amount per socket */
> +			default_size = (internal_config.memory * cpu_per_socket[socket])
> +			                / rte_lcore_count();
> +
> +			/* Limit to maximum available memory on socket */
> +			default_size = RTE_MIN(default_size, 
get_socket_mem_size(socket));
> +
> +			/* Update sizes */
> +			memory[socket] = default_size;
> +			total_size -= default_size;
> +		}
> +
> +		/*
> +		 * If some memory is remaining, try to allocate it by getting all
> +		 * available memory from sockets, one after the other
> +		 */
> +		for (socket = 0; socket < RTE_MAX_NUMA_NODES && total_size != 0;
> socket++) { /* take whatever is available */
> -			memory[socket] = RTE_MIN(get_socket_mem_size(socket),
> -					total_mem);
> +			default_size = RTE_MIN(get_socket_mem_size(socket) - 
memory[socket],
> +			                       total_size);
> +
> +			/* Update sizes */
> +			memory[socket] += default_size;
> +			total_size -= default_size;
>  		}
> +	}
> +
> +	for (socket = 0; socket < RTE_MAX_NUMA_NODES && total_mem != 0; socket++)
> { /* skips if the memory on specific socket wasn't requested */
>  		for (i = 0; i < num_hp_info && memory[socket] != 0; i++){
>  			hp_used[i].hugedir = hp_info[i].hugedir;