Re: [PATCH 4/6] sctp multistream scheduling: extend socket API

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With regard to sched_priv and sched_internal, here are some explanations:

sched_priv: Parameters of a scheduling algorithm that should be
configured by the user. For example, the weight of each stream in WFQ
or the priority of each stream in priority queue.

sched_internal: Internal states used by a scheduling algorithm. Not
all algorithms need it. For example, memoryless algorithms such as
priority queue don't need it. Priority queue only look at the current
state and pick the highest priority chunk available. But for WFQ, we
need to store the remaining token of each stream in sched_internal. We
also need to memorize who is scheduled last time.

In the current design, sched_priv is specific to a socket. Even if two
sockets both use WFQ, they may set different weights for different
streams. sched_internal is specific to each association/queue. Even if
two associations use the same scheduling algorithm with exactly the
same configuration, the internal states are separate.

I cannot move these states in to sched_ops since sched_ops is specific
to each scheduling algorithm.

Yaogong

On Thu, Jun 3, 2010 at 7:43 AM, Vlad Yasevich <vladislav.yasevich@xxxxxx> wrote:
>
>
> Wei Yongjun wrote:
>>> Augment SCTP socket API with a new socket option to choose and
>>> configure scheduling algorithm.
>>>
>>> Signed-off-by: Yaogong Wang <ywang15@xxxxxxxx>
>>> ---
>>> diff -uprN -X linux-2.6.32.8/Documentation/dontdiff
>>> p3/include/net/sctp/structs.h p4/include/net/sctp/structs.h
>>> --- p3/include/net/sctp/structs.h    2010-06-02 12:57:24.000000000 -0700
>>> +++ p4/include/net/sctp/structs.h    2010-06-02 12:58:11.000000000 -0700
>>> @@ -326,6 +326,8 @@ struct sctp_sock {
>>>
>>>      /* Multistream scheduling  */
>>>      const struct sctp_sched_ops *sched_ops;
>>> +    __u32 sched_priv_len;
>>> +    __u16 *sched_priv;
>>>
>>>      struct sctp_initmsg initmsg;
>>>      struct sctp_rtoinfo rtoinfo;
>>> @@ -1691,6 +1693,8 @@ struct sctp_association {
>>>
>>>      /* Multistream scheduling  */
>>>      const struct sctp_sched_ops *sched_ops;
>>> +    __u32 sched_priv_len;
>>> +    __u16 *sched_priv;
>>>
>>
>> I also see you add "__u16 *sched_internal;" to asoc, those are
>> the sche base values, and are different between sche.
>> The socket and assoc may not want to know the detail, raw data
>> is enough for them, and if we want to add a new sche, we do
>> not change the struct sctp_sock or struct sctp_association every
>> time.
>
> I agree.  These should probably go into sched_ops.
>
> -vlad
>
>>
>>>      /* Heartbeat interval: The endpoint sends out a Heartbeat chunk to
>>>       * the destination address every heartbeat interval. This value
>>> diff -uprN -X linux-2.6.32.8/Documentation/dontdiff
>>> p3/include/net/sctp/user.h p4/include/net/sctp/user.h
>>> --- p3/include/net/sctp/user.h       2010-05-28 10:59:23.000000000 -0700
>>> +++ p4/include/net/sctp/user.h       2010-05-28 11:54:47.000000000 -0700
>>> @@ -67,6 +67,8 @@ enum sctp_optname {
>>>  #define SCTP_ASSOCINFO SCTP_ASSOCINFO
>>>      SCTP_INITMSG,
>>>  #define SCTP_INITMSG SCTP_INITMSG
>>> +    SCTP_SCHED,
>>> +#define SCTP_SCHED SCTP_SCHED
>>>      SCTP_NODELAY,   /* Get/set nodelay option. */
>>>  #define SCTP_NODELAY        SCTP_NODELAY
>>>      SCTP_AUTOCLOSE,
>>> @@ -171,8 +173,22 @@ struct sctp_initmsg {
>>>      __u16 sinit_max_init_timeo;
>>>  };
>>>
>>> +/*
>>> + * SCTP Scheduling Structure (SCTP_SCHED)
>>> + *
>>> + *   cmsg_level    cmsg_type      cmsg_data[]
>>> + *   ------------  ------------   ----------------------
>>> + *   IPPROTO_SCTP  SCTP_SCHED     struct sctp_sched
>>> + *
>>> + */
>>>  #define SCTP_SCHED_NAME_MAX 16
>>>
>>> +struct sctp_sched {
>>> +    char  ssched_name[SCTP_SCHED_NAME_MAX];
>>> +    __u32 ssched_priv_len;
>>> +    __u16 ssched_priv[0];
>>> +};
>>> +
>>>  /*
>>>   * 5.2.2 SCTP Header Information Structure (SCTP_SNDRCV)
>>>   *
>>> diff -uprN -X linux-2.6.32.8/Documentation/dontdiff
>>> p3/net/sctp/associola.c p4/net/sctp/associola.c
>>> --- p3/net/sctp/associola.c  2010-06-02 12:57:06.000000000 -0700
>>> +++ p4/net/sctp/associola.c  2010-06-02 12:57:57.000000000 -0700
>>> @@ -187,6 +187,14 @@ static struct sctp_association *sctp_ass
>>>
>>>      /* Multistream scheduling  */
>>>      asoc->sched_ops = sp->sched_ops;
>>> +    asoc->sched_priv_len = sp->sched_priv_len;
>>> +    if (asoc->sched_priv_len) {
>>> +            asoc->sched_priv = kmalloc(asoc->sched_priv_len, gfp);
>>> +            if (!asoc->sched_priv)
>>> +                    goto fail_init;
>>> +            memcpy(asoc->sched_priv, sp->sched_priv, asoc->sched_priv_len);
>>> +    } else
>>> +            asoc->sched_priv = NULL;
>>>
>>>      /* Allocate storage for the ssnmap after the inbound and outbound
>>>       * streams have been negotiated during Init.
>>> @@ -464,6 +472,8 @@ static void sctp_association_destroy(str
>>>  {
>>>      SCTP_ASSERT(asoc->base.dead, "Assoc is not dead", return);
>>>
>>> +    kfree(asoc->sched_priv);
>>> +
>>>      sctp_endpoint_put(asoc->ep);
>>>      sock_put(asoc->base.sk);
>>>
>>> diff -uprN -X linux-2.6.32.8/Documentation/dontdiff
>>> p3/net/sctp/socket.c p4/net/sctp/socket.c
>>> --- p3/net/sctp/socket.c     2010-05-28 12:38:09.000000000 -0700
>>> +++ p4/net/sctp/socket.c     2010-05-28 12:36:37.000000000 -0700
>>> @@ -2580,6 +2580,50 @@ static int sctp_setsockopt_initmsg(struc
>>>      return 0;
>>>  }
>>>
>>> +/* Set the multistream scheduling algorithm*/
>>> +static int sctp_setsockopt_sched(struct sock *sk, char __user *optval,
>>> +                                            unsigned int optlen)
>>> +{
>>> +    struct sctp_sched *ssched = NULL;
>>> +    struct sctp_sock *sp = sctp_sk(sk);
>>> +    int ret = 0;
>>> +
>>> +    if (optlen < sizeof(struct sctp_sched))
>>> +            return -EINVAL;
>>> +
>>> +    ssched = kmalloc(optlen, GFP_KERNEL);
>>> +    if (!ssched)
>>> +            return -ENOMEM;
>>> +
>>> +    if (copy_from_user(ssched, optval, optlen)) {
>>> +            ret = -EFAULT;
>>> +            goto out;
>>> +    }
>>> +
>>> +    if (optlen != sizeof(struct sctp_sched) + ssched->ssched_priv_len) {
>>> +            ret = -EINVAL;
>>> +            goto out;
>>> +    }
>>> +
>>> +    ret = sctp_set_sched(sk, ssched->ssched_name);
>>> +    if (ret)
>>> +            goto out;
>>> +    sp->sched_priv_len = ssched->ssched_priv_len;
>>> +    kfree(sp->sched_priv);
>>> +    if (sp->sched_priv_len) {
>>> +            sp->sched_priv = kmalloc(sp->sched_priv_len, GFP_KERNEL);
>>> +            if (!sp->sched_priv) {
>>> +                    ret = -ENOMEM;
>>> +                    goto out;
>>> +            }
>>> +            memcpy(sp->sched_priv, ssched->ssched_priv, sp->sched_priv_len);
>>> +    }
>>> +
>>> +out:
>>> +    kfree(ssched);
>>> +    return ret;
>>> +}
>>> +
>>>  /*
>>>   * 7.1.14 Set default send parameters (SCTP_DEFAULT_SEND_PARAM)
>>>   *
>>> @@ -3417,6 +3461,9 @@ SCTP_STATIC int sctp_setsockopt(struct s
>>>              retval = sctp_setsockopt_partial_delivery_point(sk, optval, optlen);
>>>              break;
>>>
>>> +    case SCTP_SCHED:
>>> +            retval = sctp_setsockopt_sched(sk, optval, optlen);
>>> +            break;
>>>      case SCTP_INITMSG:
>>>              retval = sctp_setsockopt_initmsg(sk, optval, optlen);
>>>              break;
>>> @@ -3642,7 +3689,10 @@ SCTP_STATIC int sctp_init_sock(struct so
>>>      sp->initmsg.sinit_max_attempts   = sctp_max_retrans_init;
>>>      sp->initmsg.sinit_max_init_timeo = sctp_rto_max;
>>>
>>> +    /* Initialize default scheduling algorithm  */
>>>      sp->sched_ops = sctp_default_sched_ops;
>>> +    sp->sched_priv_len = 0;
>>> +    sp->sched_priv = NULL;
>>>
>>>      /* Initialize default RTO related parameters.  These parameters can
>>>       * be modified for with the SCTP_RTOINFO socket option.
>>> @@ -3735,6 +3785,9 @@ SCTP_STATIC void sctp_destroy_sock(struc
>>>
>>>      SCTP_DEBUG_PRINTK("sctp_destroy_sock(sk: %p)\n", sk);
>>>
>>> +    sctp_cleanup_sched(sk);
>>> +    kfree(sctp_sk(sk)->sched_priv);
>>> +
>>>      /* Release our hold on the endpoint. */
>>>      ep = sctp_sk(sk)->ep;
>>>      sctp_endpoint_free(ep);
>>> @@ -4351,6 +4404,35 @@ static int sctp_getsockopt_initmsg(struc
>>>      return 0;
>>>  }
>>>
>>> +/* Get the multistream scheduling algorithm*/
>>> +static int sctp_getsockopt_sched(struct sock *sk, int len, char __user *optval,
>>> +                                                    int __user *optlen)
>>> +{
>>> +    struct sctp_sched *ssched;
>>> +    int sz = sizeof(struct sctp_sched) + sctp_sk(sk)->sched_priv_len;
>>> +    int ret = 0;
>>> +
>>> +    if (len < sz)
>>> +            return -EINVAL;
>>> +    if (put_user(sz, optlen))
>>> +            return -EFAULT;
>>> +
>>> +    ssched = kmalloc(sz, GFP_KERNEL);
>>> +    if (!ssched)
>>> +            return -EFAULT;
>>> +    memcpy(ssched->ssched_name, sctp_sk(sk)->sched_ops->name,
>>> +                                    SCTP_SCHED_NAME_MAX);
>>> +    ssched->ssched_priv_len = sctp_sk(sk)->sched_priv_len;
>>> +    memcpy(ssched->ssched_priv, sctp_sk(sk)->sched_priv,
>>> +                                    ssched->ssched_priv_len);
>>> +
>>> +    if (copy_to_user(optval, ssched, sz))
>>> +            ret = -EFAULT;
>>> +
>>> +    kfree(ssched);
>>> +    return ret;
>>> +}
>>> +
>>>  static int sctp_getsockopt_peer_addrs_num_old(struct sock *sk, int len,
>>>                                            char __user *optval,
>>>                                            int __user *optlen)
>>> @@ -5605,6 +5687,9 @@ SCTP_STATIC int sctp_getsockopt(struct s
>>>      case SCTP_INITMSG:
>>>              retval = sctp_getsockopt_initmsg(sk, len, optval, optlen);
>>>              break;
>>> +    case SCTP_SCHED:
>>> +            retval = sctp_getsockopt_sched(sk, len, optval, optlen);
>>> +            break;
>>>      case SCTP_GET_PEER_ADDRS_NUM_OLD:
>>>              retval = sctp_getsockopt_peer_addrs_num_old(sk, len, optval,
>>>                                                          optlen);
>>> --
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>>>
>>>
>>
>



-- 
========================
Yaogong Wang, PhD candidate
Department of Computer Science
North Carolina State University
http://www4.ncsu.edu/~ywang15/
========================
--
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