Re: [dpdk-dev] [PATCH v2 2/2] mempool/nb_stack: add non-blocking stack mempool

["Gavin Hu (Arm Technology China)" <Gavin.Hu@arm.com>]

> -----Original Message-----
> From: Eads, Gage <gage.eads@intel.com>
> Sent: Thursday, January 17, 2019 11:16 PM
> To: Richardson, Bruce <bruce.richardson@intel.com>
> Cc: Gavin Hu (Arm Technology China) <Gavin.Hu@arm.com>;
> dev@dpdk.org; olivier.matz@6wind.com; arybchenko@solarflare.com;
> Ananyev, Konstantin <konstantin.ananyev@intel.com>; Honnappa
> Nagarahalli <Honnappa.Nagarahalli@arm.com>; Ruifeng Wang (Arm
> Technology China) <Ruifeng.Wang@arm.com>; Phil Yang (Arm Technology
> China) <Phil.Yang@arm.com>
> Subject: RE: [dpdk-dev] [PATCH v2 2/2] mempool/nb_stack: add non-
> blocking stack mempool
>
>
>
> > -----Original Message-----
> > From: Richardson, Bruce
> > Sent: Thursday, January 17, 2019 8:21 AM
> > To: Eads, Gage <gage.eads@intel.com>
> > Cc: Gavin Hu (Arm Technology China) <Gavin.Hu@arm.com>;
> dev@dpdk.org;
> > olivier.matz@6wind.com; arybchenko@solarflare.com; Ananyev,
> Konstantin
> > <konstantin.ananyev@intel.com>; Honnappa Nagarahalli
> > <Honnappa.Nagarahalli@arm.com>; Ruifeng Wang (Arm Technology
> China)
> > <Ruifeng.Wang@arm.com>; Phil Yang (Arm Technology China)
> > <Phil.Yang@arm.com>
> > Subject: Re: [dpdk-dev] [PATCH v2 2/2] mempool/nb_stack: add non-
> blocking
> > stack mempool
> >
> > On Thu, Jan 17, 2019 at 02:11:22PM +0000, Eads, Gage wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: Gavin Hu (Arm Technology China) [mailto:Gavin.Hu@arm.com]
> > > > Sent: Thursday, January 17, 2019 2:06 AM
> > > > To: Eads, Gage <gage.eads@intel.com>; dev@dpdk.org
> > > > Cc: olivier.matz@6wind.com; arybchenko@solarflare.com; Richardson,
> > > > Bruce <bruce.richardson@intel.com>; Ananyev, Konstantin
> > > > <konstantin.ananyev@intel.com>; Honnappa Nagarahalli
> > > > <Honnappa.Nagarahalli@arm.com>; Ruifeng Wang (Arm Technology
> China)
> > > > <Ruifeng.Wang@arm.com>; Phil Yang (Arm Technology China)
> > > > <Phil.Yang@arm.com>
> > > > Subject: RE: [dpdk-dev] [PATCH v2 2/2] mempool/nb_stack: add
> > > > non-blocking stack mempool
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: dev <dev-bounces@dpdk.org> On Behalf Of Gage Eads
> > > > > Sent: Wednesday, January 16, 2019 6:33 AM
> > > > > To: dev@dpdk.org
> > > > > Cc: olivier.matz@6wind.com; arybchenko@solarflare.com;
> > > > > bruce.richardson@intel.com; konstantin.ananyev@intel.com
> > > > > Subject: [dpdk-dev] [PATCH v2 2/2] mempool/nb_stack: add
> > > > > non-blocking stack mempool
> > > > >
> > > > > This commit adds support for non-blocking (linked list based)
> > > > > stack mempool handler. The stack uses a 128-bit compare-and-
> swap
> > > > > instruction, and thus is limited to x86_64. The 128-bit CAS
> > > > > atomically updates the stack top pointer and a modification
> > > > > counter, which protects against the ABA problem.
> > > > >
> > > > > In mempool_perf_autotest the lock-based stack outperforms the
> non-
> > > > > blocking handler*, however:
> > > > > - For applications with preemptible pthreads, a lock-based stack's
> > > > >   worst-case performance (i.e. one thread being preempted while
> > > > >   holding the spinlock) is much worse than the non-blocking stack's.
> > > > > - Using per-thread mempool caches will largely mitigate the
> performance
> > > > >   difference.
> > > > >
> > > > > *Test setup: x86_64 build with default config, dual-socket Xeon
> > > > > E5-2699 v4, running on isolcpus cores with a tickless scheduler.
> > > > > The lock-based stack's rate_persec was 1x-3.5x the non-blocking
> stack's.
> > > > >
> > > > > Signed-off-by: Gage Eads <gage.eads@intel.com>
> > > > > ---
> > > > >  MAINTAINERS                                        |   4 +
> > > > >  config/common_base                                 |   1 +
> > > > >  doc/guides/prog_guide/env_abstraction_layer.rst    |   5 +
> > > > >  drivers/mempool/Makefile                           |   3 +
> > > > >  drivers/mempool/meson.build                        |   5 +
> > > > >  drivers/mempool/nb_stack/Makefile                  |  23 ++++
> > > > >  drivers/mempool/nb_stack/meson.build               |   4 +
> > > > >  drivers/mempool/nb_stack/nb_lifo.h                 | 147
> > > > > +++++++++++++++++++++
> > > > >  drivers/mempool/nb_stack/rte_mempool_nb_stack.c    | 125
> > > > > ++++++++++++++++++
> > > > >  .../nb_stack/rte_mempool_nb_stack_version.map      |   4 +
> > > > >  mk/rte.app.mk                                      |   7 +-
> > > > >  11 files changed, 326 insertions(+), 2 deletions(-)  create mode
> > > > > 100644 drivers/mempool/nb_stack/Makefile  create mode 100644
> > > > > drivers/mempool/nb_stack/meson.build
> > > > >  create mode 100644 drivers/mempool/nb_stack/nb_lifo.h
> > > > >  create mode 100644
> > > > > drivers/mempool/nb_stack/rte_mempool_nb_stack.c
> > > > >  create mode 100644
> > > > > drivers/mempool/nb_stack/rte_mempool_nb_stack_version.map
> > > > >
> > > > > diff --git a/MAINTAINERS b/MAINTAINERS index
> 470f36b9c..5519d3323
> > > > > 100644
> > > > > --- a/MAINTAINERS
> > > > > +++ b/MAINTAINERS
> > > > > @@ -416,6 +416,10 @@ M: Artem V. Andreev
> > > > > <artem.andreev@oktetlabs.ru>
> > > > >  M: Andrew Rybchenko <arybchenko@solarflare.com>
> > > > >  F: drivers/mempool/bucket/
> > > > >
> > > > > +Non-blocking stack memory pool
> > > > > +M: Gage Eads <gage.eads@intel.com>
> > > > > +F: drivers/mempool/nb_stack/
> > > > > +
> > > > >
> > > > >  Bus Drivers
> > > > >  -----------
> > > > > diff --git a/config/common_base b/config/common_base index
> > > > > 964a6956e..8a51f36b1 100644
> > > > > --- a/config/common_base
> > > > > +++ b/config/common_base
> > > > > @@ -726,6 +726,7 @@ CONFIG_RTE_LIBRTE_MEMPOOL_DEBUG=n
> #
> > > > > CONFIG_RTE_DRIVER_MEMPOOL_BUCKET=y
> > > > >  CONFIG_RTE_DRIVER_MEMPOOL_BUCKET_SIZE_KB=64
> > > > > +CONFIG_RTE_DRIVER_MEMPOOL_NB_STACK=y
> > > >
> > > > NAK,  as this applies to x86_64 only, it will break arm/ppc and even
> > > > 32bit i386 configurations.
> > > >
> > >
> > > Hi Gavin,
> > >
> > > This patch resolves that in the make and meson build files, which
> ensure that
> > the library is only built for x86-64 targets:

Looking down to the changes with Makefile and meson.build, it will be compiled out for arm/ppc/i386. That works at least.
But having this entry in the arm/ppc/i386 configurations is very strange, since they have no such implementations.
Why not put it into defconfig_x86_64-native-linuxapp-icc/gcc/clang to limit the scope?

> > >
> > > diff --git a/drivers/mempool/Makefile b/drivers/mempool/Makefile
> index
> > > 28c2e8360..895cf8a34 100644
> > > --- a/drivers/mempool/Makefile
> > > +++ b/drivers/mempool/Makefile
> > > @@ -10,6 +10,9 @@ endif
> > >  ifeq ($(CONFIG_RTE_EAL_VFIO)$(CONFIG_RTE_LIBRTE_FSLMC_BUS),yy)
> > >  DIRS-$(CONFIG_RTE_LIBRTE_DPAA2_MEMPOOL) += dpaa2  endif
> > > +ifeq ($(CONFIG_RTE_ARCH_X86_64),y)
> > > +DIRS-$(CONFIG_RTE_DRIVER_MEMPOOL_NB_STACK) += nb_stack endif
> > >
> > > diff --git a/drivers/mempool/nb_stack/meson.build
> > > b/drivers/mempool/nb_stack/meson.build
> > > new file mode 100644
> > > index 000000000..4a699511d
> > > --- /dev/null
> > > +++ b/drivers/mempool/nb_stack/meson.build
> > > @@ -0,0 +1,8 @@
> > > +# SPDX-License-Identifier: BSD-3-Clause # Copyright(c) 2019 Intel
> > > +Corporation
> > > +
> > > +if arch_subdir != 'x86' or cc.sizeof('void *') == 4
> > > +build = false
> > > +endif
> > > +
> >
> > Minor suggestion:
> > Can be simplified to "build = dpdk_conf.has('RTE_ARCH_X86_64')", I
> believe.
> >
> > /Bruce
>
> Sure, I'll switch to that check in v4.
>
> Thanks,
> Gage
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