[ovs-dev] [v4 03/12] dpif-netdev: Add study function to select the best mfex function

Amber, Kumar kumar.amber at intel.com
Tue Jun 29 03:46:12 UTC 2021


Hi Flavio,

Thanks again and my replies are inline.

> -----Original Message-----
> From: Flavio Leitner <fbl at sysclose.org>
> Sent: Monday, June 28, 2021 8:22 AM
> To: Amber, Kumar <kumar.amber at intel.com>
> Cc: dev at openvswitch.org; i.maximets at ovn.org
> Subject: Re: [ovs-dev] [v4 03/12] dpif-netdev: Add study function to select
> the best mfex function
> 
> 
> Hi,
> 
> On Thu, Jun 17, 2021 at 09:57:45PM +0530, Kumar Amber wrote:
> > The study function runs all the available implementations of
> > miniflow_extract and makes a choice whose hitmask has maximum hits
> and
> > sets the mfex to that function.
> >
> > Study can be run at runtime using the following command:
> >
> > $ ovs-appctl dpif-netdev/miniflow-parser-set study
> 
> Nice!
>

😊
 
> 
> >
> > Signed-off-by: Kumar Amber <kumar.amber at intel.com>
> > Co-authored-by: Harry van Haaren <harry.van.haaren at intel.com>
> > Signed-off-by: Harry van Haaren <harry.van.haaren at intel.com>
> > ---
> >  lib/automake.mk                   |   1 +
> >  lib/dpif-netdev-extract-study.c   | 119 ++++++++++++++++++++++++++++++
> >  lib/dpif-netdev-private-extract.c |   5 ++
> >  lib/dpif-netdev-private-extract.h |  14 +++-
> >  4 files changed, 138 insertions(+), 1 deletion(-)  create mode 100644
> > lib/dpif-netdev-extract-study.c
> >
> > diff --git a/lib/automake.mk b/lib/automake.mk index
> > 6657b9ae5..3080bb04a 100644
> > --- a/lib/automake.mk
> > +++ b/lib/automake.mk
> > @@ -114,6 +114,7 @@ lib_libopenvswitch_la_SOURCES = \
> >  	lib/dpif-netdev.c \
> >  	lib/dpif-netdev.h \
> >  	lib/dpif-netdev-private-dfc.c \
> > +	lib/dpif-netdev-extract-study.c \
> 
> Wrong order?
> 

Fixed in v5.

> >  	lib/dpif-netdev-private-dfc.h \
> >  	lib/dpif-netdev-private-dpcls.h \
> >  	lib/dpif-netdev-private-dpif.c \
> > diff --git a/lib/dpif-netdev-extract-study.c
> > b/lib/dpif-netdev-extract-study.c new file mode 100644 index
> > 000000000..d063d040c
> > --- /dev/null
> > +++ b/lib/dpif-netdev-extract-study.c
> > @@ -0,0 +1,119 @@
> > +/*
> > + * Copyright (c) 2021 Intel.
> > + *
> > + * Licensed under the Apache License, Version 2.0 (the "License");
> > + * you may not use this file except in compliance with the License.
> > + * You may obtain a copy of the License at:
> > + *
> > + *     http://www.apache.org/licenses/LICENSE-2.0
> > + *
> > + * Unless required by applicable law or agreed to in writing,
> > +software
> > + * distributed under the License is distributed on an "AS IS" BASIS,
> > + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
> implied.
> > + * See the License for the specific language governing permissions
> > +and
> > + * limitations under the License.
> > + */
> > +
> > +#include <config.h>
> > +#include <errno.h>
> > +#include <stdint.h>
> > +#include <string.h>
> > +
> > +#include "dpif-netdev-private-extract.h"
> > +#include "dpif-netdev-private-thread.h"
> > +#include "openvswitch/vlog.h"
> > +#include "ovs-thread.h"
> > +
> > +VLOG_DEFINE_THIS_MODULE(dpif_mfex_extract_study);
> > +
> > +/* Max size of packets to be compared. */
> 
> Size or number?
> 

Typo fixed.

> > +#define MFEX_MAX_COUNT (128)
> > +
> > +/* This value is the threshold for the amount of packets that
> > + * must hit on the optimized miniflow extract before it will be
> > + * accepted and used in the datapath after the study phase. */
> > +#define MFEX_MIN_HIT_COUNT_FOR_USE (MFEX_MAX_COUNT / 2)
> > +
> > +/* Struct to hold miniflow study stats. */ struct study_stats {
> > +    uint32_t pkt_count;
> > +    uint32_t impl_hitcount[MFEX_IMPLS_MAX_SIZE];
> > +};
> > +
> > +/* Define per thread data to hold the study stats. */
> > +DEFINE_PER_THREAD_MALLOCED_DATA(struct study_stats *,
> study_stats);
> > +
> > +/* Allocate per thread PMD pointer space for study_stats. */ static
> > +inline struct study_stats *
> > +get_study_stats(void)
> 
> Please define some prefix name for this module, like for example
> mfex_study_<something>, to have a convention.
>

Using mfex_study_get_study_stats as name in v5.
 
> 
> > +{
> > +    struct study_stats *stats = study_stats_get();
> > +    if (OVS_UNLIKELY(!stats)) {
> > +       stats = xzalloc(sizeof *stats);
> > +       study_stats_set_unsafe(stats);
> > +    }
> > +    return stats;
> > +}
> > +
> > +uint32_t
> > +mfex_study_traffic(struct dp_packet_batch *packets,
> > +                   struct netdev_flow_key *keys,
> > +                   uint32_t keys_size, odp_port_t in_port,
> > +                   void *pmd_handle)
> > +{
> > +    uint32_t hitmask = 0;
> > +    uint32_t mask = 0;
> > +    struct dp_netdev_pmd_thread *pmd = pmd_handle;
> > +    struct dpif_miniflow_extract_impl *miniflow_funcs;
> > +    uint32_t impl_count =
> dpif_miniflow_extract_info_get(&miniflow_funcs);
> > +    struct study_stats *stats = get_study_stats();
> > +
> > +    /* Run traffic optimized miniflow_extract to collect the hitmask
> > +     * to be compared after certain packets have been hit to choose
> > +     * the best miniflow_extract version for that traffic. */
> > +    for (int i = MFEX_IMPL_START_IDX; i < impl_count; i++) {
> > +        if (miniflow_funcs[i].available) {
> > +            hitmask = miniflow_funcs[i].extract_func(packets, keys, keys_size,
> > +                                                     in_port, pmd_handle);
> > +            stats->impl_hitcount[i] += count_1bits(hitmask);
> > +
> > +            /* If traffic is not classified than we dont overwrite the keys
> > +             * array in minfiflow implementations so its safe to create a
> > +             * mask for all those packets whose miniflow have been created.
> */
> > +            mask |= hitmask;
> > +        }
> > +    }
> > +    stats->pkt_count += dp_packet_batch_size(packets);
> > +
> > +    /* Choose the best implementation after a minimum packets have
> been
> > +     * processed. */
> > +    if (stats->pkt_count >= MFEX_MAX_COUNT) {
> > +        uint32_t best_func_index = MFEX_IMPL_START_IDX;
> > +        uint32_t max_hits = 0;
> > +        for (int i = MFEX_IMPL_START_IDX; i < impl_count; i++) {
> > +            if (stats->impl_hitcount[i] > max_hits) {
> > +                max_hits = stats->impl_hitcount[i];
> > +                best_func_index = i;
> > +            }
> > +        }
> > +
> > +        if (max_hits >= MFEX_MIN_HIT_COUNT_FOR_USE) {
> > +            /* Set the implementation to index with max_hits. */
> > +            pmd->miniflow_extract_opt =
> > +                        miniflow_funcs[best_func_index].extract_func;
> > +            VLOG_INFO("MFEX study chose impl %s: (hits %d/%d pkts)\n",
> > +                      miniflow_funcs[best_func_index].name, max_hits,
> > +                      stats->pkt_count);
> 
> No need to terminate with \n when using VLOG_*
> 

Removed in all Vlogs.
> > +        } else {
> > +            /* Set the implementation to null for default miniflow. */
> > +            pmd->miniflow_extract_opt = NULL;
> > +            VLOG_INFO("Not enough packets matched (%d/%d), disabling"
> > +                      " optimized MFEX.\n", max_hits, stats->pkt_count);
> > +        }
> > +        /* Reset stats so that study function can be called again
> > +         * for next traffic type and optimal function ptr can be
> > +         * choosen. */
> > +        memset(stats, 0, sizeof(struct study_stats));
> > +    }
> > +    return mask;
> > +}
> > diff --git a/lib/dpif-netdev-private-extract.c
> > b/lib/dpif-netdev-private-extract.c
> > index 0741c19f9..d86268a1d 100644
> > --- a/lib/dpif-netdev-private-extract.c
> > +++ b/lib/dpif-netdev-private-extract.c
> > @@ -42,6 +42,11 @@ static struct dpif_miniflow_extract_impl
> mfex_impls[] = {
> >          .extract_func = NULL,
> >          .name = "disable",
> >      },
> > +    {
> > +        .probe = NULL,
> > +        .extract_func = mfex_study_traffic,
> > +        .name = "study",
> > +    },
> >  };
> >
> >  BUILD_ASSERT_DECL(MFEX_IMPLS_MAX_SIZE > ARRAY_SIZE(mfex_impls));
> 
> Since there is no dynamic registration of mfex implementation, then using
> the enum suggested on an earlier patch we would have the last entry as
> replacement for MFEX_IMPLS_MAX_SIZE.
> 
> 
Using MFEX_IMPLS_MAX as end Enum marker.

> > diff --git a/lib/dpif-netdev-private-extract.h
> > b/lib/dpif-netdev-private-extract.h
> > index 455a7b590..3ada413bb 100644
> > --- a/lib/dpif-netdev-private-extract.h
> > +++ b/lib/dpif-netdev-private-extract.h
> > @@ -27,7 +27,7 @@
> >  /* Skip the autovalidator study and null when iterating all available
> >   * miniflow implementations.
> >   */
> > -#define MFEX_IMPL_START_IDX (1)
> > +#define MFEX_IMPL_START_IDX (3)
> >
> >  /* Forward declarations. */
> >  struct dp_packet;
> > @@ -106,4 +106,16 @@ dpif_miniflow_extract_autovalidator(struct
> dp_packet_batch *batch,
> >                                      uint32_t keys_size, odp_port_t in_port,
> >                                      void *pmd_handle);
> >
> > +/* Retrieve the number of packets by studying packets using different
> > +miniflow
> > + * implementations to choose the best implementation using the
> > +maximum hitmask
> > + * count.
> > + * On error, returns a zero for no packets.
> > + * On success, returns mask of the packets hit.
> > + */
> > +uint32_t
> > +mfex_study_traffic(struct dp_packet_batch *packets,
> > +                   struct netdev_flow_key *keys,
> > +                   uint32_t keys_size, odp_port_t in_port,
> > +                   void *pmd_handle);
> > +
> >  #endif /* DPIF_NETDEV_AVX512_EXTRACT */
> > --
> > 2.25.1
> >
> > _______________________________________________
> > dev mailing list
> > dev at openvswitch.org
> > https://mail.openvswitch.org/mailman/listinfo/ovs-dev
> 
> --
> fbl


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