[ovs-dev] [PATCH v1 04/14] netdev-dpdk: Serialise non-pmds mbufs' alloc/free.

Lam, Tiago tiago.lam at intel.com
Wed Jul 4 16:10:39 UTC 2018


On 03/07/2018 10:49, Eelco Chaudron wrote:
> 
> 
> On 28 Jun 2018, at 17:41, Tiago Lam wrote:
> 
>> A new mutex, 'nonpmd_mp_mutex', has been introduced to serialise
>> allocation and free operations by non-pmd threads on a given mempool.
>>
>> free_dpdk_buf() has been modified to make use of the introduced mutex.
>>
>> Signed-off-by: Tiago Lam <tiago.lam at intel.com>
>> ---
>>  lib/netdev-dpdk.c | 30 +++++++++++++++++++++++++++---
>>  1 file changed, 27 insertions(+), 3 deletions(-)
>>
>> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
>> index c5c6aab..5c62d85 100644
>> --- a/lib/netdev-dpdk.c
>> +++ b/lib/netdev-dpdk.c
>> @@ -294,6 +294,16 @@ static struct ovs_mutex dpdk_mp_mutex 
>> OVS_ACQ_AFTER(dpdk_mutex)
>>  static struct ovs_list dpdk_mp_free_list 
>> OVS_GUARDED_BY(dpdk_mp_mutex)
>>      = OVS_LIST_INITIALIZER(&dpdk_mp_free_list);
>>
>> +/* This mutex must be used by non pmd threads when allocating or 
>> freeing
>> + * mbufs through mempools, when outside of the `non_pmd_mutex` mutex, 
>> in struct
>> + * dp_netdev.
>> + * The reason, as pointed out in the "Known Issues" section in DPDK's 
>> EAL docs,
>> + * is that the implementation on which mempool is based off is 
>> non-preemptable.
>> + * Since non-pmds may end up not being pinned this could lead to the 
>> preemption
>> + * between non-pmds performing operations on the same mempool, which 
>> could lead
>> + * to memory corruption. */
>> +static struct ovs_mutex nonpmd_mp_mutex = OVS_MUTEX_INITIALIZER;
>> +
>>  /* Wrapper for a mempool released but not yet freed. */
>>  struct dpdk_mp {
>>       struct rte_mempool *mp;
>> @@ -462,6 +472,8 @@ struct netdev_rxq_dpdk {
>>      dpdk_port_t port_id;
>>  };
>>
>> +static bool dpdk_thread_is_pmd(void);
>> +
>>  static void netdev_dpdk_destruct(struct netdev *netdev);
>>  static void netdev_dpdk_vhost_destruct(struct netdev *netdev);
>>
>> @@ -495,6 +507,12 @@ dpdk_buf_size(int mtu)
>>                       NETDEV_DPDK_MBUF_ALIGN);
>>  }
>>
>> +static bool
>> +dpdk_thread_is_pmd(void)
>> +{
>> +     return rte_lcore_id() != NON_PMD_CORE_ID;
>> +}
>> +
>>  /* Allocates an area of 'sz' bytes from DPDK.  The memory is zero'ed.
>>   *
>>   * Unlike xmalloc(), this function can return NULL on failure. */
>> @@ -505,11 +523,17 @@ dpdk_rte_mzalloc(size_t sz)
>>  }
>>
>>  void
>> -free_dpdk_buf(struct dp_packet *p)
>> +free_dpdk_buf(struct dp_packet *packet)
>>  {
>> -    struct rte_mbuf *pkt = (struct rte_mbuf *) p;
>> +    if (!dpdk_thread_is_pmd()) {
>> +        ovs_mutex_lock(&nonpmd_mp_mutex);
>> +    }
>>
>> -    rte_pktmbuf_free(pkt);
>> +    rte_pktmbuf_free((struct rte_mbuf *) packet);
> 
> Rather than casting it, it should be &packet->mbuf, some one might 
> change the order in the dp_packet structure.
> 

Missed this one. I'll do this for v2, thanks.

Tiago.


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