Re: [dpdk-dev] [PATCH 3/4] eal/arm: Enable lpm/table/pipeline libs

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

On Wed, Dec 02, 2015 at 09:13:51PM +0800, Jianbo Liu wrote:
> On 2 December 2015 at 18:39, Jerin Jacob <jerin.jacob@caviumnetworks.com> wrote:
> > On Wed, Dec 02, 2015 at 05:49:41PM +0800, Jianbo Liu wrote:
> >> On 2 December 2015 at 16:03, Jerin Jacob <jerin.jacob@caviumnetworks.com> wrote:
> >> > On Wed, Dec 02, 2015 at 02:54:52PM +0800, Jianbo Liu wrote:
> >> >> On 2 December 2015 at 00:41, Jerin Jacob <jerin.jacob@caviumnetworks.com> wrote:
> >> >> > On Tue, Dec 01, 2015 at 01:41:15PM -0500, Jianbo Liu wrote:
> >> >> >> Adds ARM NEON support for lpm.
> >> >> >> And enables table/pipeline libraries which depend on lpm.
> >> >> >
> >> >> > I already sent the patch on the same yesterday.
> >> >> > We can converge the patches after the discussion.
> >> >> > Please check "[dpdk-dev] [PATCH 0/3] add lpm support for NEON" on ml
> >> >> >
> >> >> Yes, I have read your patch. But there are many differences, so I sent
> >> >> mine for your reviewing :)
> >> >>
> >> >> >
> >> >> >>
> >> >> >> Signed-off-by: Jianbo Liu <jianbo.liu@linaro.org>
> >> >> >> ---
> >> >> >>  config/defconfig_arm-armv7a-linuxapp-gcc          |  3 -
> >> >> >>  config/defconfig_arm64-armv8a-linuxapp-gcc        |  3 -
> >> >> >>  lib/librte_eal/common/include/arch/arm/rte_vect.h | 28 ++++++++++
> >> >> >>  lib/librte_lpm/rte_lpm.h                          | 68 ++++++++++++++++-------
> >> >> >>  4 files changed, 77 insertions(+), 25 deletions(-)
> >> >> >>
> >> >> >> diff --git a/config/defconfig_arm-armv7a-linuxapp-gcc b/config/defconfig_arm-armv7a-linuxapp-gcc
> >> >> >> index cbebd64..efffa1f 100644
> >> >> >> --- a/config/defconfig_arm-armv7a-linuxapp-gcc
> >> >> >> +++ b/config/defconfig_arm-armv7a-linuxapp-gcc
> >> >> >> @@ -53,9 +53,6 @@ CONFIG_RTE_LIBRTE_KNI=n
> >> >> >>  CONFIG_RTE_EAL_IGB_UIO=n
> >> >> >>
> >> >> >>  # fails to compile on ARM
> >> >> >> -CONFIG_RTE_LIBRTE_LPM=n
> >> >> >> -CONFIG_RTE_LIBRTE_TABLE=n
> >> >> >> -CONFIG_RTE_LIBRTE_PIPELINE=n
> >> >> >>  CONFIG_RTE_SCHED_VECTOR=n
> >> >> >>
> >> >> >>  # cannot use those on ARM
> >> >> >> diff --git a/config/defconfig_arm64-armv8a-linuxapp-gcc b/config/defconfig_arm64-armv8a-linuxapp-gcc
> >> >> >> index 504f3ed..57f7941 100644
> >> >> >> --- a/config/defconfig_arm64-armv8a-linuxapp-gcc
> >> >> >> +++ b/config/defconfig_arm64-armv8a-linuxapp-gcc
> >> >> >> @@ -51,7 +51,4 @@ CONFIG_RTE_LIBRTE_IVSHMEM=n
> >> >> >>  CONFIG_RTE_LIBRTE_FM10K_PMD=n
> >> >> >>  CONFIG_RTE_LIBRTE_I40E_PMD=n
> >> >> >>
> >> >> >> -CONFIG_RTE_LIBRTE_LPM=n
> >> >> >> -CONFIG_RTE_LIBRTE_TABLE=n
> >> >> >> -CONFIG_RTE_LIBRTE_PIPELINE=n
> >> >> >>  CONFIG_RTE_SCHED_VECTOR=n
> >> >> >> diff --git a/lib/librte_eal/common/include/arch/arm/rte_vect.h b/lib/librte_eal/common/include/arch/arm/rte_vect.h
> >> >> >> index a33c054..7437711 100644
> >> >> >> --- a/lib/librte_eal/common/include/arch/arm/rte_vect.h
> >> >> >> +++ b/lib/librte_eal/common/include/arch/arm/rte_vect.h
> >> >> >> @@ -41,6 +41,8 @@ extern "C" {
> >> >> >>
> >> >> >>  typedef int32x4_t xmm_t;
> >> >> >>
> >> >> >> +typedef int32x4_t __m128i;
> >> >> >> +
> >> >> >>  #define      XMM_SIZE        (sizeof(xmm_t))
> >> >> >>  #define      XMM_MASK        (XMM_SIZE - 1)
> >> >> >>
> >> >> >> @@ -53,6 +55,32 @@ typedef union rte_xmm {
> >> >> >>       double   pd[XMM_SIZE / sizeof(double)];
> >> >> >>  } __attribute__((aligned(16))) rte_xmm_t;
> >> >> >>
> >> >> >> +static __inline __m128i
> >> >> >> +_mm_set_epi32(int i3, int i2, int i1, int i0)
> >> >> >> +{
> >> >> >> +     int32_t r[4] = {i0, i1, i2, i3};
> >> >> >> +
> >> >> >> +     return vld1q_s32(r);
> >> >> >> +}
> >> >> >> +
> >> >> >> +static __inline __m128i
> >> >> >> +_mm_loadu_si128(__m128i *p)
> >> >> >> +{
> >> >> >> +     return vld1q_s32((int32_t *)p);
> >> >> >> +}
> >> >> >> +
> >> >> >> +static __inline __m128i
> >> >> >> +_mm_set1_epi32(int i)
> >> >> >> +{
> >> >> >> +     return vdupq_n_s32(i);
> >> >> >> +}
> >> >> >> +
> >> >> >> +static __inline __m128i
> >> >> >> +_mm_and_si128(__m128i a, __m128i b)
> >> >> >> +{
> >> >> >> +     return vandq_s32(a, b);
> >> >> >> +}
> >> >> >> +
> >> >
> >> > IMO, it's not always good to emulate GCC defined intrinsics of
> >> > other architecture. What if a legacy DPDK application has such mappings
> >> > then BOOM, multiple definition, which one is correct? which one
> >> > to comment it out? Integration pain starts for DPDK library consumer:-(
> >> >
> >> They can include rte_vect.h in build/include directly, which is linked correctly
> >> to the one for that ARCH, so there is no need to worry about.
> >
> > I think you missed the point,I was trying to say that
> > legacy DPDK application and third party stacks uses SSE2NEON kind of
> > libraries
> > for quick integration, for example, something like this
> > https://github.com/jratcliff63367/sse2neon/blob/master/SSE2NEON.h
> >
> > AND they include "rte_lpm.h"(it internally includes rte_vect.h)
> > that lead to multiple definition and its not good.
> >
> But you will have similar issue since "typedef int32x4_t __m128i"
> appears in both your patch and this header file.

I just tested it, it won't break, back to back "typedef int32x4_t __m128i"
is fine(unlike inline function).

my intention to keep __m128i "as is"  because changing the __m128i to rte_???
something would break the ABI.


> 
> >>
> >>
> >> >> >
> >> >> > IMO, it makes sense to not emulate the SSE intrinsics with NEON
> >> >> > Let's create the rte_vect_* as required. look at the existing patch.
> >> >> >
> >> >> I thought of creating a layer of SIMD over all the platforms before.
> >> >> But can't you see it make things complicated, considering there are
> >> >> only few simple intrinsic to implement?
> >> >
> >> > Not true, There were, a lot of SSE intrinsics needs be to emulated for ACL NEON
> >> > implementation if I were to take this approach and emulation comes with
> >> > the cost.
> >> >
> >> No, I will not re-implement all the intrinsic like that .
> >> I only do with the simple intrinsic, such as load/store, as you said below.
> >
> > but you forced to add _mm_and_si128 also to the list and emulated
> > _mm_and_si128 intrinsic. Am just saying no emulation.
> >
> I means simple intrinsic, not load/store only.
> Depends on how you define emulation. Actually, these simple intrisinic
> could be only one NEON instruction, and will not bring cost.
> 
> >
> >>
> >> > So my take is,
> >> > lets the each architecture implementation for specific SIMD version of DPDK
> >> > API in the library should have the freedom to implement the API in
> >> > NATIVE.
> >> >
> >> > And let's create only rte_vect_* abstraction only for using
> >> > that API/library. Which boils down to have very minimal rte_vect_*
> >> > abstraction to load, store, set not beyond that.
> >> >
> >> > This makes clear "contract" between DPDK library and the applications.
> >> > and make easy for remaning new architecture  porting effort in DPDK.
> >> >
> >> Agree.
> >> But I reuse existing intrinsic names, and you recreate new ones.
> >> And I try to do as few changes as possible, and try to avoid any
> >> mistaken which may cause code un-compiled.
> >
> > Its trival to verify. Just compile it
> >
> >> I think it's design level question, we need to hear what others talk about it.
> >>
> >> > Imagine how your proposed function will look like if new architecture
> >> > wants to implement "optimized" version of rte_lpm_lookupx4
> >> >
> >> There is no optimization for this (simple) rte_lpm_lookupx4, otherwise
> >> you have done that in your patch.
> >> If there is for other new platform, defintely they should do like
> >> yours, as you did for NEON ACL.
> >>
> >> >
> >> >> If do so, we also need to explain to others how to use these interfaces.
> >> >> Besides, this patch did the smallest changes to the original code, and
> >> >> more likely to be accepted by others.
> >> >
> >> > other patch makes no changes to IA version of rte_lpm_lookupx4.I thought
> >> > that make reviewer easy to review the changes in architecture
> >> > perspective.
> >> >
> >> As I know, they don't enable LPM for PPC, and ARM is the first one to
> >> touch this issue.
> >>
> >> >>
> >> >> >
> >> >> >>  #ifdef RTE_ARCH_ARM
> >> >> >>  /* NEON intrinsic vqtbl1q_u8() is not supported in ARMv7-A(AArch32) */
> >> >> >>  static __inline uint8x16_t
> >> >> >> diff --git a/lib/librte_lpm/rte_lpm.h b/lib/librte_lpm/rte_lpm.h
> >> >> >> index c299ce2..c76c07d 100644
> >> >> >> --- a/lib/librte_lpm/rte_lpm.h
> >> >> >> +++ b/lib/librte_lpm/rte_lpm.h
> >> >> >> @@ -361,6 +361,47 @@ rte_lpm_lookup_bulk_func(const struct rte_lpm *lpm, const uint32_t * ips,
> >> >> >>  /* Mask four results. */
> >> >> >>  #define       RTE_LPM_MASKX4_RES     UINT64_C(0x00ff00ff00ff00ff)
> >> >> >>
> >> >> >> +#if defined(RTE_ARCH_ARM) || defined(RTE_ARCH_ARM64)
> >> >> >
> >> >> > Separate out arm implementation to the different header file.
> >> >> > Too many ifdef looks odd in the header file and difficult to manage.
> >> >> >
> >> >> But there are many ifdefs already.
> >> >> And It seems unreasonable to add a new file only for one small function.
> >> >>
> >> >
> >> > small or big, its matter of each architecture to have
> >> > the freedom for the optimized version for the implementation.
> >> >
> >> > What if  other architecture demands to write this function in assembly
> >> > or restructure it for performance improvement?
> >> >
> >> If there is such demands, should do like that.
> >> But I don't see any restructure in your patch, and you still follow
> >> the logic as x86, is it worth adding a new file?
> >
> > SIMD Logic on getting  4 indexes for tbl24[] is different.
> >
> > /* get 4 indexes for tbl24[]. */
> > i24 = _mm_srli_epi32(ip, CHAR_BIT);
> >
> > /* extract values from tbl24[] */
> > idx = _mm_cvtsi128_si64(i24);
> > i24 = _mm_srli_si128(i24, sizeof(uint64_t));
> >
> > tbl[0] = *(const uint16_t *)&lpm->tbl24[(uint32_t)idx];
> > tbl[1] = *(const uint16_t *)&lpm->tbl24[idx >> 32];
> >
> > idx = _mm_cvtsi128_si64(i24);
> >
> > tbl[2] = *(const uint16_t *)&lpm->tbl24[(uint32_t)idx];
> > tbl[3] = *(const uint16_t *)&lpm->tbl24[idx >> 32];
> >
> > VS
> >
> > /* extract values from tbl24[] */
> > idx = vgetq_lane_u64((uint64x2_t)i24, 0);
> >
> > tbl[0] = *(const uint16_t *)&lpm->tbl24[(uint32_t)idx];
> > tbl[1] = *(const uint16_t *)&lpm->tbl24[idx >> 32];
> >
> > idx = vgetq_lane_u64((uint64x2_t)i24, 1);
> >
> > tbl[2] = *(const uint16_t *)&lpm->tbl24[(uint32_t)idx];
> > tbl[3] = *(const uint16_t *)&lpm->tbl24[idx >> 32];
> >
> It's only the optimazation of part of code in that function. I did the
> similar in my patch.
> But, looking from the whole, this function is not restructured, and
> the logic is the same as x86.
> 
> >>
> >> >
> >> >> >
> >> >> >> +static inline void
> >> >> >> +rte_lpm_tbl24_val4(const struct rte_lpm *lpm, int32x4_t ip, uint16_t tbl[4])
> >> >> >> +{
> >> >> >> +     uint32x4_t i24;
> >> >> >> +     uint32_t idx[4];
> >> >> >> +
> >> >> >> +     /* get 4 indexes for tbl24[]. */
> >> >> >> +     i24 = vshrq_n_u32(vreinterpretq_u32_s32(ip), CHAR_BIT);
> >> >> >> +     vst1q_u32(idx, i24);
> >> >> >> +
> >> >> >> +     /* extract values from tbl24[] */
> >> >> >> +     tbl[0] = *(const uint16_t *)&lpm->tbl24[idx[0]];
> >> >> >> +     tbl[1] = *(const uint16_t *)&lpm->tbl24[idx[1]];
> >> >> >> +     tbl[2] = *(const uint16_t *)&lpm->tbl24[idx[2]];
> >> >> >> +     tbl[3] = *(const uint16_t *)&lpm->tbl24[idx[3]];
> >> >> >> +}
> >> >> >
> >> >> > Nice. There is an improvement in this portion code wrt my patch. This is
> >> >> > a candidate for convergence.
> >> >> >
> >> >> >
> >> >> >> +#else
> >> >> >> +static inline void
> >> >> >> +rte_lpm_tbl24_val4(const struct rte_lpm *lpm, __m128i ip, uint16_t tbl[4])
> >> >> >> +{
> >> >> >> +     __m128i i24;
> >> >> >> +     uint64_t idx;
> >> >> >> +
> >> >> >> +     /* get 4 indexes for tbl24[]. */
> >> >> >> +     i24 = _mm_srli_epi32(ip, CHAR_BIT);
> >> >> >> +
> >> >> >> +     /* extract values from tbl24[] */
> >> >> >> +     idx = _mm_cvtsi128_si64(i24);
> >> >> >> +     i24 = _mm_srli_si128(i24, sizeof(uint64_t));
> >> >> >> +
> >> >> >> +     tbl[0] = *(const uint16_t *)&lpm->tbl24[(uint32_t)idx];
> >> >> >> +     tbl[1] = *(const uint16_t *)&lpm->tbl24[idx >> 32];
> >> >> >> +
> >> >> >> +     idx = _mm_cvtsi128_si64(i24);
> >> >> >> +
> >> >> >> +     tbl[2] = *(const uint16_t *)&lpm->tbl24[(uint32_t)idx];
> >> >> >> +     tbl[3] = *(const uint16_t *)&lpm->tbl24[idx >> 32];
> >> >> >> +}
> >> >> >> +#endif
> >> >> >> +
> >> >> >>  /**
> >> >> >>   * Lookup four IP addresses in an LPM table.
> >> >> >>   *
> >> >> >> @@ -381,17 +422,19 @@ rte_lpm_lookup_bulk_func(const struct rte_lpm *lpm, const uint32_t * ips,
> >> >> >>   *   if lookup would fail.
> >> >> >>   */
> >> >> >>  static inline void
> >> >> >> +#if defined(RTE_ARCH_ARM) || defined(RTE_ARCH_ARM64)
> >> >> >> +rte_lpm_lookupx4(const struct rte_lpm *lpm, int32x4_t ip, uint16_t hop[4],
> >> >> >> +     uint16_t defv)
> >> >> >
> >> >> > This would call for change in the change the ABI,
> >> >> > IMO, __m128i can be used to represent 128bit vector to avoid ABI chang
> >> >> >
> >> >> This redefine rte_lpm_lookupx4 is unncessary, I will remove it, so no
> >> >> ABI change.
> >> >> And there only one ifdef for ARM platforms left.
> >> >>
> >> >> >
> >> >> >> +#else
> >> >> > separate out arm implementation to the different header file. Too many
> >> >> > ifdef looks odd in the header file.
> >> >> >
> >> >> > Could you  rebase your patch based on existing patch and send the
> >> >> > improvement portion as separate patch or I can send update patch with
> >> >> > your improvements and with your signoff.
> >> >> >
> >> >> >
> >> >> >>  rte_lpm_lookupx4(const struct rte_lpm *lpm, __m128i ip, uint16_t hop[4],
> >> >> >>       uint16_t defv)
> >> >> >> +#endif
> >> >> >>  {
> >> >> >> -     __m128i i24;
> >> >> >>       rte_xmm_t i8;
> >> >> >>       uint16_t tbl[4];
> >> >> >> -     uint64_t idx, pt;
> >> >> >> -
> >> >> >> -     const __m128i mask8 =
> >> >> >> -             _mm_set_epi32(UINT8_MAX, UINT8_MAX, UINT8_MAX, UINT8_MAX);
> >> >> >> +     uint64_t pt;
> >> >> >>
> >> >> >> +     const __m128i mask8 = _mm_set1_epi32(UINT8_MAX);
> >> >> >>       /*
> >> >> >>        * RTE_LPM_VALID_EXT_ENTRY_BITMASK for 4 LPM entries
> >> >> >>        * as one 64-bit value (0x0300030003000300).
> >> >> >> @@ -412,20 +455,7 @@ rte_lpm_lookupx4(const struct rte_lpm *lpm, __m128i ip, uint16_t hop[4],
> >> >> >>               (uint64_t)RTE_LPM_LOOKUP_SUCCESS << 32 |
> >> >> >>               (uint64_t)RTE_LPM_LOOKUP_SUCCESS << 48);
> >> >> >>
> >> >> >> -     /* get 4 indexes for tbl24[]. */
> >> >> >> -     i24 = _mm_srli_epi32(ip, CHAR_BIT);
> >> >> >> -
> >> >> >> -     /* extract values from tbl24[] */
> >> >> >> -     idx = _mm_cvtsi128_si64(i24);
> >> >> >> -     i24 = _mm_srli_si128(i24, sizeof(uint64_t));
> >> >> >> -
> >> >> >> -     tbl[0] = *(const uint16_t *)&lpm->tbl24[(uint32_t)idx];
> >> >> >> -     tbl[1] = *(const uint16_t *)&lpm->tbl24[idx >> 32];
> >> >> >> -
> >> >> >> -     idx = _mm_cvtsi128_si64(i24);
> >> >> >> -
> >> >> >> -     tbl[2] = *(const uint16_t *)&lpm->tbl24[(uint32_t)idx];
> >> >> >> -     tbl[3] = *(const uint16_t *)&lpm->tbl24[idx >> 32];
> >> >> >> +     rte_lpm_tbl24_val4(lpm, ip, tbl);
> >> >> >>
> >> >> >>       /* get 4 indexes for tbl8[]. */
> >> >> >>       i8.x = _mm_and_si128(ip, mask8);
> >> >> >> --
> >> >> >> 1.8.3.1
> >> >> >>