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In-Reply-To: <4135e426-5a6f-c36a-d048-382c07f16b0a@kernel.org>
From:   Nick Richardson <richardsonnick@google.com>
Date:   Tue, 17 Aug 2021 19:55:21 -0400
Message-ID: <CAGr-3gm+BWdEVpaGdTmhdGyt9POiSohTZo9hKGjioAzWcp=jEA@mail.gmail.com>
Subject: Re: [PATCH v2 2/3] pktgen: Add imix distribution bins
To:     Nathan Chancellor <nathan@kernel.org>
Cc:     Naresh Kamboju <naresh.kamboju@linaro.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, nrrichar@ncsu.edu,
        Philip Romanov <promanov@google.com>,
        Arun Kalyanasundaram <arunkaly@google.com>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Di Zhu <zhudi21@huawei.com>, Leesoo Ahn <dev@ooseel.net>,
        Ye Bin <yebin10@huawei.com>,
        Yejune Deng <yejune.deng@gmail.com>,
        Netdev <netdev@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        Linux-Next Mailing List <linux-next@vger.kernel.org>,
        lkft-triage@lists.linaro.org, Mark Brown <broonie@kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>
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On Tue, Aug 17, 2021 at 6:27 PM Nathan Chancellor <nathan@kernel.org> wrote:
>
> On 8/17/2021 3:17 PM, Nick Richardson wrote:
> > On Wed, 11 Aug 2021 at 00:32, Nicholas Richardson
> > <richardsonnick@google.com> wrote:
> >>
> >> From: Nick Richardson <richardsonnick@google.com>
> >>
> >> In order to represent the distribution of imix packet sizes, a
> >> pre-computed data structure is used. It features 100 (IMIX_PRECISION)
> >> "bins". Contiguous ranges of these bins represent the respective
> >> packet size of each imix entry. This is done to avoid the overhead of
> >> selecting the correct imix packet size based on the corresponding weights.
> >>
> >> Example:
> >> imix_weights 40,7 576,4 1500,1
> >> total_weight = 7 + 4 + 1 = 12
> >>
> >> pkt_size 40 occurs 7/total_weight = 58% of the time
> >> pkt_size 576 occurs 4/total_weight = 33% of the time
> >> pkt_size 1500 occurs 1/total_weight = 9% of the time
> >>
> >> We generate a random number between 0-100 and select the corresponding
> >> packet size based on the specified weights.
> >> Eg. random number = 358723895 % 100 = 65
> >> Selects the packet size corresponding to index:65 in the pre-computed
> >> imix_distribution array.
> >> An example of the  pre-computed array is below:
> >>
> >> The imix_distribution will look like the following:
> >> 0        ->  0 (index of imix_entry.size == 40)
> >> 1        ->  0 (index of imix_entry.size == 40)
> >> 2        ->  0 (index of imix_entry.size == 40)
> >> [...]    ->  0 (index of imix_entry.size == 40)
> >> 57       ->  0 (index of imix_entry.size == 40)
> >> 58       ->  1 (index of imix_entry.size == 576)
> >> [...]    ->  1 (index of imix_entry.size == 576)
> >> 90       ->  1 (index of imix_entry.size == 576)
> >> 91       ->  2 (index of imix_entry.size == 1500)
> >> [...]    ->  2 (index of imix_entry.size == 1500)
> >> 99       ->  2 (index of imix_entry.size == 1500)
> >>
> >> Create and use "bin" representation of the imix distribution.
> >>
> >> Signed-off-by: Nick Richardson <richardsonnick@google.com>
> >> ---
> >>   net/core/pktgen.c | 41 +++++++++++++++++++++++++++++++++++++++++
> >>   1 file changed, 41 insertions(+)
> >>
> >> diff --git a/net/core/pktgen.c b/net/core/pktgen.c
> >> index a7e45eaccef7..ac1de15000e2 100644
> >> --- a/net/core/pktgen.c
> >> +++ b/net/core/pktgen.c
> >> @@ -177,6 +177,7 @@
> >>   #define MPLS_STACK_BOTTOM htonl(0x00000100)
> >>   /* Max number of internet mix entries that can be specified in imix_weights. */
> >>   #define MAX_IMIX_ENTRIES 20
> >> +#define IMIX_PRECISION 100 /* Precision of IMIX distribution */
> >>
> >>   #define func_enter() pr_debug("entering %s\n", __func__);
> >>
> >> @@ -354,6 +355,8 @@ struct pktgen_dev {
> >>          /* IMIX */
> >>          unsigned int n_imix_entries;
> >>          struct imix_pkt imix_entries[MAX_IMIX_ENTRIES];
> >> +       /* Maps 0-IMIX_PRECISION range to imix_entry based on probability*/
> >> +       __u8 imix_distribution[IMIX_PRECISION];
> >>
> >>          /* MPLS */
> >>          unsigned int nr_labels; /* Depth of stack, 0 = no MPLS */
> >> @@ -483,6 +486,7 @@ static void pktgen_stop_all_threads(struct pktgen_net *pn);
> >>
> >>   static void pktgen_stop(struct pktgen_thread *t);
> >>   static void pktgen_clear_counters(struct pktgen_dev *pkt_dev);
> >> +static void fill_imix_distribution(struct pktgen_dev *pkt_dev);
> >
> > Linux next 20210813 tag arm builds failed due to following build errors.
> >
> > Regressions found on arm:
> >
> >   - build/gcc-10-ixp4xx_defconfig
> >   - build/gcc-10-orion5x_defconfig
> >   - build/gcc-10-multi_v5_defconfig
> >
> > net/core/pktgen.c:489:13: warning: 'fill_imix_distribution' used but
> > never defined
> >   static void fill_imix_distribution(struct pktgen_dev *pkt_dev);
> >               ^~~~~~~~~~~~~~~~~~~~~~
> > ERROR: modpost: "fill_imix_distribution" [net/core/pktgen.ko] undefined!
> > make[2]: *** [scripts/Makefile.modpost:150: modules-only.symvers] Error 1
> > make[2]: *** Deleting file 'modules-only.symvers'
> > make[2]: Target '__modpost' not remade because of errors.
> > make[1]: *** [Makefile:1918: modules] Error 2
> >
> > Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> >
> > Steps to reproduce:
> >
> > # TuxMake is a command line tool and Python library that provides
> > # portable and repeatable Linux kernel builds across a variety of
> > # architectures, toolchains, kernel configurations, and make targets.
> > #
> > # TuxMake supports the concept of runtimes.
> > # See https://docs.tuxmake.org/runtimes/, for that to work it requires
> > # that you install podman or docker on your system.
> > #
> > # To install tuxmake on your system globally:
> > # sudo pip3 install -U tuxmake
> > #
> > # See https://docs.tuxmake.org/ for complete documentation.
> >
> > tuxmake --runtime podman --target-arch arm --toolchain gcc-10
> > --kconfig orion5x_defconfig
> >
> >
> > On Sat, Aug 14, 2021 at 1:13 AM Naresh Kamboju
> > <naresh.kamboju@linaro.org> wrote:
> >>
> >> On Wed, 11 Aug 2021 at 00:32, Nicholas Richardson
> >> <richardsonnick@google.com> wrote:
> >>>
> >>> From: Nick Richardson <richardsonnick@google.com>
> >>>
> >>> In order to represent the distribution of imix packet sizes, a
> >>> pre-computed data structure is used. It features 100 (IMIX_PRECISION)
> >>> "bins". Contiguous ranges of these bins represent the respective
> >>> packet size of each imix entry. This is done to avoid the overhead of
> >>> selecting the correct imix packet size based on the corresponding weights.
> >>>
> >>> Example:
> >>> imix_weights 40,7 576,4 1500,1
> >>> total_weight = 7 + 4 + 1 = 12
> >>>
> >>> pkt_size 40 occurs 7/total_weight = 58% of the time
> >>> pkt_size 576 occurs 4/total_weight = 33% of the time
> >>> pkt_size 1500 occurs 1/total_weight = 9% of the time
> >>>
> >>> We generate a random number between 0-100 and select the corresponding
> >>> packet size based on the specified weights.
> >>> Eg. random number = 358723895 % 100 = 65
> >>> Selects the packet size corresponding to index:65 in the pre-computed
> >>> imix_distribution array.
> >>> An example of the  pre-computed array is below:
> >>>
> >>> The imix_distribution will look like the following:
> >>> 0        ->  0 (index of imix_entry.size == 40)
> >>> 1        ->  0 (index of imix_entry.size == 40)
> >>> 2        ->  0 (index of imix_entry.size == 40)
> >>> [...]    ->  0 (index of imix_entry.size == 40)
> >>> 57       ->  0 (index of imix_entry.size == 40)
> >>> 58       ->  1 (index of imix_entry.size == 576)
> >>> [...]    ->  1 (index of imix_entry.size == 576)
> >>> 90       ->  1 (index of imix_entry.size == 576)
> >>> 91       ->  2 (index of imix_entry.size == 1500)
> >>> [...]    ->  2 (index of imix_entry.size == 1500)
> >>> 99       ->  2 (index of imix_entry.size == 1500)
> >>>
> >>> Create and use "bin" representation of the imix distribution.
> >>>
> >>> Signed-off-by: Nick Richardson <richardsonnick@google.com>
> >>> ---
> >>>   net/core/pktgen.c | 41 +++++++++++++++++++++++++++++++++++++++++
> >>>   1 file changed, 41 insertions(+)
> >>>
> >>> diff --git a/net/core/pktgen.c b/net/core/pktgen.c
> >>> index a7e45eaccef7..ac1de15000e2 100644
> >>> --- a/net/core/pktgen.c
> >>> +++ b/net/core/pktgen.c
> >>> @@ -177,6 +177,7 @@
> >>>   #define MPLS_STACK_BOTTOM htonl(0x00000100)
> >>>   /* Max number of internet mix entries that can be specified in imix_weights. */
> >>>   #define MAX_IMIX_ENTRIES 20
> >>> +#define IMIX_PRECISION 100 /* Precision of IMIX distribution */
> >>>
> >>>   #define func_enter() pr_debug("entering %s\n", __func__);
> >>>
> >>> @@ -354,6 +355,8 @@ struct pktgen_dev {
> >>>          /* IMIX */
> >>>          unsigned int n_imix_entries;
> >>>          struct imix_pkt imix_entries[MAX_IMIX_ENTRIES];
> >>> +       /* Maps 0-IMIX_PRECISION range to imix_entry based on probability*/
> >>> +       __u8 imix_distribution[IMIX_PRECISION];
> >>>
> >>>          /* MPLS */
> >>>          unsigned int nr_labels; /* Depth of stack, 0 = no MPLS */
> >>> @@ -483,6 +486,7 @@ static void pktgen_stop_all_threads(struct pktgen_net *pn);
> >>>
> >>>   static void pktgen_stop(struct pktgen_thread *t);
> >>>   static void pktgen_clear_counters(struct pktgen_dev *pkt_dev);
> >>> +static void fill_imix_distribution(struct pktgen_dev *pkt_dev);
> >>
> >> Linux next 20210813 tag arm builds failed due to following build errors.
> >>
> >> Regressions found on arm:
> >>
> >>   - build/gcc-10-ixp4xx_defconfig
> >>   - build/gcc-10-orion5x_defconfig
> >>   - build/gcc-10-multi_v5_defconfig
> >>
> >> net/core/pktgen.c:489:13: warning: 'fill_imix_distribution' used but
> >> never defined
> >>   static void fill_imix_distribution(struct pktgen_dev *pkt_dev);
> >>               ^~~~~~~~~~~~~~~~~~~~~~
> >> ERROR: modpost: "fill_imix_distribution" [net/core/pktgen.ko] undefined!
> >> make[2]: *** [scripts/Makefile.modpost:150: modules-only.symvers] Error 1
> >> make[2]: *** Deleting file 'modules-only.symvers'
> >> make[2]: Target '__modpost' not remade because of errors.
> >> make[1]: *** [Makefile:1918: modules] Error 2
> >>
> >> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> >>
> >> Steps to reproduce:
> >>
> >> # TuxMake is a command line tool and Python library that provides
> >> # portable and repeatable Linux kernel builds across a variety of
> >> # architectures, toolchains, kernel configurations, and make targets.
> >> #
> >> # TuxMake supports the concept of runtimes.
> >> # See https://docs.tuxmake.org/runtimes/, for that to work it requires
> >> # that you install podman or docker on your system.
> >> #
> >> # To install tuxmake on your system globally:
> >> # sudo pip3 install -U tuxmake
> >> #
> >> # See https://docs.tuxmake.org/ for complete documentation.
> >>
> >> tuxmake --runtime podman --target-arch arm --toolchain gcc-10
> >> --kconfig orion5x_defconfig
> >>
> >> --
> >> Linaro LKFT
> >> https://lkft.linaro.org
> >
> > Thanks for the reply Naresh. Do you have any ideas on how to resolve
> > this error? Pktgen already defines a couple of function prototypes
> > before they are declared and that seems to be the cause of this error
> > message.
>
> The problem is that you declare and use fill_imix_distribution()
> unconditionally in the file but fill_imix_distribution() is only defined
> if CONFIG_XFRM is set, resulting in this error if CONFIG_XFRM is not set.
>
> Should fill_imix_distribution() be moved out of that block or does it
> truly depend on CONFIG_XFRM? If it does, should the use of
> fill_imix_distribution() be guarded by CONFIG_XFRM as well?
>
> Cheers,
> Nathan

Good catch, thanks. Fixed in v3.