Hi Eelco,

Pls find my comments inline.

> -----Original Message-----
> From: Eelco Chaudron <[email protected]>
> Sent: Monday, July 12, 2021 9:17 PM
> To: Amber, Kumar <[email protected]>
> Cc: [email protected]; [email protected]; [email protected]; Van
> Haaren, Harry <[email protected]>; Ferriter, Cian
> <[email protected]>; Stokes, Ian <[email protected]>
> Subject: Re: [v9 06/12] dpif-netdev: Add packet count and core id paramters 
> for
> study
> 
> 
> 
> On 12 Jul 2021, at 7:51, kumar Amber wrote:
> 
> > From: Kumar Amber <[email protected]>
> >
> > This commit introduces additional command line paramter for mfex study
> > function. If user provides additional packet out it is used in study
> > to compare minimum packets which must be processed else a default
> > value is choosen.
> > Also introduces a third paramter for choosing a particular pmd core.
> >
> > $ ovs-appctl dpif-netdev/miniflow-parser-set study 500 3
> >
> > Signed-off-by: Kumar Amber <[email protected]>
> >
> > ---
> > v9:
> > - fix review comments Flavio
> > v7:
> > - change the command paramters for core_id and study_pkt_cnt
> > v5:
> > - fix review comments(Ian, Flavio, Eelco)
> > - introucde pmd core id parameter
> > ---
> > ---
> >  Documentation/topics/dpdk/bridge.rst |  39 ++++++++-
> >  lib/dpif-netdev-extract-study.c      |  26 +++++-
> >  lib/dpif-netdev-private-extract.h    |   9 ++
> >  lib/dpif-netdev.c                    | 121 +++++++++++++++++++++++++--
> >  4 files changed, 181 insertions(+), 14 deletions(-)
> >
> > diff --git a/Documentation/topics/dpdk/bridge.rst
> > b/Documentation/topics/dpdk/bridge.rst
> > index 4db416ddd..c31067c51 100644
> > --- a/Documentation/topics/dpdk/bridge.rst
> > +++ b/Documentation/topics/dpdk/bridge.rst
> > @@ -284,12 +284,45 @@ command also shows whether the CPU supports
> each implementation ::
> >
> >  An implementation can be selected manually by the following command ::
> >
> > -    $ ovs-appctl dpif-netdev/miniflow-parser-set study
> > +    $ ovs-appctl dpif-netdev/miniflow-parser-set [-pmd core_id] [name]
> > +                                                 [study_cnt]
> >
> > -Also user can select the study implementation which studies the
> > traffic for
> > +The above command has two optional parameters: study_cnt and core_id.
> > +The core_id set a particular miniflow extract function to a specific
> 
> The core_id sets
> 
> > +pmd thread on the core. Third parameter study_cnt, which is specific
> 
> The third parameter
> 

Fixed both typos.

> > +to study and ignored by other implementations, means how many packets
> > +are needed to choose the best implementation.
> > +
> > +The user can select the study implementation which studies the
> > +traffic for
> >  a specific number of packets by applying all available implementaions
> > of
> 
> implementations
> 
> >  miniflow extract and than chooses the one with most optimal result
> > for that
> 
> and then chooses ... with the most optimal
> 

Fixed these 2 as well.

> > -traffic pattern.
> > +traffic pattern. The user can optionally provide an packet count
> > +[study_cnt] parameter which is the minimum number of packets that OVS
> > +must study before choosing an optimal implementation. If no packet
> > +count is provided, then the default value, 128 is chosen. Also, as
> > +there is no synchronization point between threads, one PMD thread
> > +might still be running a previous round, and can now decide on earlier 
> > data.
> > +
> > +The per packet count is a global value, and parallel `study()`
> > +executions with
> 
> Should study() just be study?
>

Changed
 
> > +differing packet counts will use the most recent count value provided by
> usser.
> > +
> > +Study can be selected with packet count by the following command ::
> > +
> > +    $ ovs-appctl dpif-netdev/miniflow-parser-set study 1024
> > +
> > +Study can be selected with packet count and explicit PMD selection by
> > +the following command ::
> > +
> > +    $ ovs-appctl dpif-netdev/miniflow-parser-set -pmd 3 study 1024
> > +
> > +In the above command the last parameter is the CORE ID of the PMD
> > +thread and this can also be used to explicitly set the miniflow
> > +extraction function pointer on different PMD threads.
> > +
> > +Scalar can be selected on core 3 by the following command where study
> > +count can be put as any arbitary number or left blank::
> 
> arbitrary
> 

Fixed.
> > +
> > +    $ ovs-appctl dpif-netdev/miniflow-parser-set -pmd 3 scalar
> >
> >  Miniflow Extract Validation
> >  ~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > diff --git a/lib/dpif-netdev-extract-study.c
> > b/lib/dpif-netdev-extract-study.c index a19759bd9..2dc3faf83 100644
> > --- a/lib/dpif-netdev-extract-study.c
> > +++ b/lib/dpif-netdev-extract-study.c
> > @@ -25,7 +25,7 @@
> >
> >  VLOG_DEFINE_THIS_MODULE(dpif_mfex_extract_study);
> >
> > -static uint32_t mfex_study_pkts_count = 0;
> > +static uint32_t mfex_study_pkts_count = MFEX_MAX_PKT_COUNT;
> >
> >  /* Struct to hold miniflow study stats. */  struct study_stats { @@
> > -48,6 +48,28 @@ mfex_study_get_study_stats_ptr(void)
> >      return stats;
> >  }
> >
> > +uint32_t mfex_set_study_pkt_cnt(uint32_t pkt_cmp_count,
> > +                                const char *name)
> 
> This needs to be int, not uint32_t as you return a negative value on error.
> 

Nice point done.

> > +{
> > +    struct dpif_miniflow_extract_impl *miniflow_funcs;
> > +    dpif_mfex_impl_info_get(&miniflow_funcs);
> > +
> > +    /* If the packet count is set and implementation called is study then
> > +     * set packet counter to requested number else set the packet counter
> > +     * to default number.
> > +     */
> > +    if ((strcmp(miniflow_funcs[MFEX_IMPL_STUDY].name, name) == 0) &&
> > +        (pkt_cmp_count != 0)) {
> > +
> > +        atomic_uintptr_t *study_pck_cnt = (void *)&mfex_study_pkts_count;
> > +        atomic_store_relaxed(study_pck_cnt, (uintptr_t) pkt_cmp_count
> > + );
> 
> This looks odd, define the mfex_study_pkts_count as an atomic_uint32_t and
> store/read the value.
>

Changed to atomic.
 
> > +
> > +        return 0;
> > +    }
> > +
> > +    return -EINVAL;
> > +}
> > +
> >  uint32_t
> >  mfex_study_traffic(struct dp_packet_batch *packets,
> >                     struct netdev_flow_key *keys, @@ -86,7 +108,7 @@
> > mfex_study_traffic(struct dp_packet_batch *packets,
> >      /* Choose the best implementation after a minimum packets have been
> >       * processed.
> >       */
> > -    if (stats->pkt_count >= MFEX_MAX_PKT_COUNT) {
> > +    if (stats->pkt_count >= mfex_study_pkts_count) {
> 
> If we set it atomically, we also need to read it atomically.
> 

Changed to atomic variable type for mfex_study_pkts_count and hence can be kept 
like it is .

> >          uint32_t best_func_index = MFEX_IMPL_START_IDX;
> >          uint32_t max_hits = 0;
> >          for (int i = MFEX_IMPL_START_IDX; i < MFEX_IMPL_MAX; i++) {
> > diff --git a/lib/dpif-netdev-private-extract.h
> > b/lib/dpif-netdev-private-extract.h
> > index 32b7ccbb3..cbc660156 100644
> > --- a/lib/dpif-netdev-private-extract.h
> > +++ b/lib/dpif-netdev-private-extract.h
> > @@ -153,4 +153,13 @@ mfex_study_traffic(struct dp_packet_batch
> *packets,
> >                     uint32_t keys_size, odp_port_t in_port,
> >                     struct dp_netdev_pmd_thread *pmd_handle);
> >
> > +/* Sets the packet count from user to the stats for use in
> > + * study function to match against the classified packets to choose
> > + * the optimal implementation.
> > + * On error, returns EINVAL.
> 
> ,returns -EINVAL
>

Fixed.
 
> > + * On success, returns 0.
> > + */
> > +uint32_t mfex_set_study_pkt_cnt(uint32_t pkt_cmp_count,
> > +                                const char *name);
> > +
> >  #endif /* MFEX_AVX512_EXTRACT */
> > diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c index
> > 10c6f9adc..f7a05d20d 100644
> > --- a/lib/dpif-netdev.c
> > +++ b/lib/dpif-netdev.c
> > @@ -1079,17 +1079,49 @@ static void
> >  dpif_miniflow_extract_impl_set(struct unixctl_conn *conn, int argc,
> >                       const char *argv[], void *aux OVS_UNUSED)  {
> > -    /* This function requires just one parameter, the miniflow name.
> > +    /* A First optional paramter PMD thread ID can be also provided which
> > +     * allows users to set miniflow implementation on a particular pmd.
> > +     * The second paramter is the name of the function and if -pmd core_id
> > +     * is not provided this is the first parameter and only mandatory one.
> > +     * The third and last one is the study-cnt which is only provided for
> > +     * study function to set the packet count.
> >       */
> > -    const char *mfex_name = argv[1];
> > +    const char *mfex_name = NULL;
> >      struct shash_node *node;
> > +    bool pmd_core_param_set = false;
> > +    struct ds reply = DS_EMPTY_INITIALIZER;
> > +
> > +    if (strcmp("-pmd", argv[1]) == 0) {
> > +        mfex_name = argv[3];
> > +        pmd_core_param_set = true;
> > +    } else {
> > +        mfex_name = argv[1];
> > +    }
> > +
> 
> Please do proper argument handling, as this will make it crash/look odd:
> 
> $ ovs-appctl dpif-netdev/miniflow-parser-set -pmd
> 
> 2021-07-12T15:25:54Z|00001|unixctl|WARN|error communicating with
> unix:/var/run/openvswitch/ovs-vswitchd.112523.ctl: End of file
> ovs-appctl: ovs-vswitchd: transaction error (End of file)
> 
> $ ovs-appctl dpif-netdev/miniflow-parser-set -pmd 1 Unknown miniflow extract
> implementation: (null).
> ovs-appctl: ovs-vswitchd: server returned an error
> 
> 

Yes this negative testing I missed but add in the test and fixed.
> 
> > +    bool pmd_thread_specified = false;
> > +    uint32_t pmd_thread_to_change = 0;
> > +    bool pmd_thread_update_ok = false;
> > +
> > +    if (pmd_core_param_set) {
> > +        if (str_to_uint(argv[2], 10, &pmd_thread_to_change)) {
> > +            pmd_thread_specified = true;
> > +        } else {
> > +            /* argv[2] isn't even a uint. return without changing 
> > anything. */
> > +            ds_put_format(&reply,
> > +                 "Error: Miniflow parser not changed, PMD thread argument"
> > +                 " passed is not valid: '%s'. Pass a valid pmd thread 
> > ID.\n",
> > +                 argv[2]);
> > +            const char *reply_str = ds_cstr(&reply);
> > +            VLOG_INFO("%s", reply_str);
> > +            unixctl_command_reply_error(conn, reply_str);
> > +            ds_destroy(&reply);
> > +            return;
> > +        }
> > +    }
> >
> > -    ovs_mutex_lock(&dp_netdev_mutex);
> >      int err = dp_mfex_impl_set_default_by_name(mfex_name);
> 
> Should we call dp_mfex_impl_set_default_by_name() if we only set a single
> PMD? I do not think, as we change the default for all.
> 

Moved the mutex down.
> >
> >      if (err) {
> > -        ovs_mutex_unlock(&dp_netdev_mutex);
> > -        struct ds reply = DS_EMPTY_INITIALIZER;
> >          char *error_desc = NULL;
> >          if (err == -EINVAL) {
> >              error_desc = "Unknown miniflow extract implementation:";
> > @@ -1108,6 +1140,49 @@ dpif_miniflow_extract_impl_set(struct
> unixctl_conn *conn, int argc,
> >          return;
> >      }
> >
> > +    /* argv[4] is optional packet count, which user can provide along with
> > +     * study function to set the minimum packet that must be matched in 
> > order
> > +     * to choose the optimal function. */
> > +    uint32_t study_ret = 0;
> > +    uint32_t pkt_cmp_count = MFEX_MAX_PKT_COUNT;
> > +
> > +    const char *study_cnt_param = NULL;
> > +    if (argc == 5) {
> > +        study_cnt_param = argv[4];
> > +    } else if ((!pmd_core_param_set) && (argc == 3)) {
> > +        study_cnt_param = argv[2];
> > +    }
> > +
> 
> Don’t really like those argc comparisons, etc, why not just deal with all the
> parameter options sweeping argv/c once, like suggested in an earlier review? I
> think I suggested looking at pmd_perf_show_cmd().
> 

Yes  it does make sense I also would like a rework  but that would require a 
lot of changes maybe I can push a rework after MFEX along with
Ipv6 , hashing and all option on patch ?  do you like the proposal ?

> > +    if (study_cnt_param) {
> > +
> 
> All these checks should have been done before doing the
> dp_mfex_impl_set_default_by_name() above, or else on failure the default has
> changed.
>

Rearranged in correct order.
 
> > +        if (str_to_uint(study_cnt_param, 10, &pkt_cmp_count)) {
> > +            study_ret = mfex_set_study_pkt_cnt(pkt_cmp_count, mfex_name);
> > +            if (study_ret == -EINVAL) {
> 
> How can this be negative, mfex_set_study_pkt_cnt() returns a uint32_t? Guess
> mfex_set_study_pkt_cnt() needs to change, see above.
> 

Fixed.
> > +                ds_put_format(&reply, "The study_pkt_cnt option is not 
> > valid"
> > +                              " for the %s implementation.\n",
> > +                              mfex_name);
> > +                const char *reply_str = ds_cstr(&reply);
> > +                unixctl_command_reply_error(conn, reply_str);
> > +                VLOG_INFO("%s", reply_str);
> > +                ds_destroy(&reply);
> > +                return;
> > +            }
> > +        } else {
> > +            ds_put_format(&reply, "Invalid study_pkt_cnt value: :
> > + %s.\n",
> 
> Please remove the extra “ :”
> 

Fixed.
> > +                          study_cnt_param);
> > +            const char *reply_str = ds_cstr(&reply);
> > +            unixctl_command_reply_error(conn, reply_str);
> > +            VLOG_INFO("%s", reply_str);
> > +            ds_destroy(&reply);
> > +            return;
> > +        }
> > +    } else {
> > +        /* Default packet compare count when packets count not * provided. 
> > */
> > +        study_ret = mfex_set_study_pkt_cnt(MFEX_MAX_PKT_COUNT,
> mfex_name);
> > +    }
> > +
> > +    ovs_mutex_lock(&dp_netdev_mutex);
> > +
> >      SHASH_FOR_EACH (node, &dp_netdevs) {
> >          struct dp_netdev_pmd_thread **pmd_list;
> >          struct dp_netdev *dp = node->data; @@ -1122,8 +1197,14 @@
> > dpif_miniflow_extract_impl_set(struct unixctl_conn *conn, int argc,
> >                  continue;
> >              }
> >
> > +            if ((pmd_thread_specified) &&
> > +                (pmd->core_id != pmd_thread_to_change)) {
> > +                continue;
> > +            }
> > +
> >              /* Initialize MFEX function pointer to the newly configured
> >               * default. */
> > +            pmd_thread_update_ok = true;
> >              atomic_uintptr_t *pmd_func = (void *) 
> > &pmd->miniflow_extract_opt;
> >              atomic_store_relaxed(pmd_func, (uintptr_t) default_func);
> >          };
> > @@ -1131,9 +1212,30 @@ dpif_miniflow_extract_impl_set(struct
> > unixctl_conn *conn, int argc,
> 
> If you add the OVS_UNUSED to argc in patch 1, you need to remove it here.
> 

Fixed.
> >
> >      ovs_mutex_unlock(&dp_netdev_mutex);
> >
> > +    /* If PMD thread was specified, but it wasn't found, return error. */
> > +    if (pmd_thread_specified && !pmd_thread_update_ok) {
> 
> Guess this check needs to happen before we set the default, although, see
> above, we should not change the default for a single thread.
> 

Re-arranged the mutex.

> > +        ds_put_format(&reply,
> > +                      "Error: Miniflow parser not changed, PMD thread %d"
> > +                      " not in use, pass a valid pmd thread ID.\n",
> > +                      pmd_thread_to_change);
> > +        const char *reply_str = ds_cstr(&reply);
> > +        VLOG_INFO("%s", reply_str);
> > +        unixctl_command_reply_error(conn, reply_str);
> > +        ds_destroy(&reply);
> > +        return;
> > +    }
> > +
> >      /* Reply with success to command. */
> > -    struct ds reply = DS_EMPTY_INITIALIZER;
> > -    ds_put_format(&reply, "Miniflow implementation set to %s.\n",
> mfex_name);
> > +    ds_put_format(&reply, "Miniflow implementation set to %s", mfex_name);
> > +    if (pmd_thread_specified) {
> > +        ds_put_format(&reply, ", on pmd thread %d", pmd_thread_to_change);
> > +    }
> > +    if (study_ret == 0) {
> > +        ds_put_format(&reply, ", studying %d packets", pkt_cmp_count);
> > +    }
> > +
> > +    ds_put_format(&reply, ".\n");
> > +
> >      const char *reply_str = ds_cstr(&reply);
> >      VLOG_INFO("%s", reply_str);
> >      unixctl_command_reply(conn, reply_str); @@ -1370,8 +1472,9 @@
> > dpif_netdev_init(void)
> >                               0, 0, dpif_netdev_impl_get,
> >                               NULL);
> >      unixctl_command_register("dpif-netdev/miniflow-parser-set",
> > -                             "miniflow_implementation_name",
> > -                             1, 1, dpif_miniflow_extract_impl_set,
> > +                             "[-pmd core] miniflow_implementation_name"
> > +                             " [study_pkt_cnt]",
> > +                             1, 5, dpif_miniflow_extract_impl_set,
> >                               NULL);
> >      unixctl_command_register("dpif-netdev/miniflow-parser-get", "",
> >                               0, 0, dpif_miniflow_extract_impl_get,
> > --
> > 2.25.1

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