From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.tuxdriver.com (charlotte.tuxdriver.com [70.61.120.58]) by dpdk.org (Postfix) with ESMTP id 1FFB0595B for ; Tue, 18 Nov 2014 15:31:27 +0100 (CET) Received: from hmsreliant.think-freely.org ([2001:470:8:a08:7aac:c0ff:fec2:933b] helo=localhost) by smtp.tuxdriver.com with esmtpsa (TLSv1:AES128-SHA:128) (Exim 4.63) (envelope-from ) id 1XqjyN-0001eZ-Lr; Tue, 18 Nov 2014 09:41:45 -0500 Date: Tue, 18 Nov 2014 09:41:38 -0500 From: Neil Horman To: Yerden Zhumabekov Message-ID: <20141118144138.GB32375@hmsreliant.think-freely.org> References: <1409724351-23786-1-git-send-email-e_zhumabekov@sts.kz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-Spam-Score: -2.9 (--) X-Spam-Status: No Cc: dev@dpdk.org Subject: Re: [dpdk-dev] [PATCH v4 3/5] hash: add fallback to software CRC32 implementation X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 18 Nov 2014 14:31:27 -0000 On Tue, Nov 18, 2014 at 08:03:40PM +0600, Yerden Zhumabekov wrote: > Initially, SSE4.2 support is detected via CPUID instruction. > > Added rte_hash_crc_set_alg() function to detect and set CRC32 > implementation if necessary. SSE4.2 is allowed by default. If it's > not available, fall back to sw implementation. > > Best available algorithm is detected upon application startup > through the constructor function rte_hash_crc_try_sse442(). > > Signed-off-by: Yerden Zhumabekov > --- > lib/librte_hash/rte_hash_crc.h | 53 ++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 51 insertions(+), 2 deletions(-) > > diff --git a/lib/librte_hash/rte_hash_crc.h b/lib/librte_hash/rte_hash_crc.h > index 15f687a..332ed99 100644 > --- a/lib/librte_hash/rte_hash_crc.h > +++ b/lib/librte_hash/rte_hash_crc.h > @@ -45,7 +45,11 @@ extern "C" { > #endif > > #include > +#ifdef RTE_MACHINE_CPUFLAG_SSE4_2 > #include > +#endif > +#include > +#include > > /* Lookup tables for software implementation of CRC32C */ > static uint32_t crc32c_tables[8][256] = {{ > @@ -363,8 +367,41 @@ crc32c_2words(uint64_t data, uint32_t init_val) > return crc; > } > > +enum crc32_alg_t { > + CRC32_SW = 0, > + CRC32_SSE42 > +}; > + > +static enum crc32_alg_t crc32_alg; > + > +/** > + * Allow or disallow use of SSE4.2 instrinsics for CRC32 hash > + * calculation. > + * > + * @param flag > + * unsigned integer flag > + * - (CRC32_SW) Don't use SSE4.2 intrinsics > + * - (CRC32_SSE42) Use SSE4.2 intrinsics if available, set by default > + */ > +static inline void > +rte_hash_crc_set_alg(enum crc32_alg_t alg) > +{ > + int sse42_supp = rte_cpu_get_flag_enabled(RTE_CPUFLAG_SSE4_2); > + enum crc32_alg_t alg_supp = sse42_supp ? CRC32_SSE42 : CRC32_SW; > + crc32_alg = (alg == CRC32_SSE42) ? alg_supp : CRC32_SW; > +} > + > +/* Best available algorithm is detected via CPUID instruction */ > +static inline void __attribute__((constructor)) > +rte_hash_crc_try_sse42(void) > +{ > + rte_hash_crc_set_alg(CRC32_SSE42); > +} > + > /** > * Use single crc32 instruction to perform a hash on a 4 byte value. > + * Fall back to software crc32 implementation in case SSE4.2 is > + * not supported > * > * @param data > * Data to perform hash on. > @@ -376,11 +413,18 @@ crc32c_2words(uint64_t data, uint32_t init_val) > static inline uint32_t > rte_hash_crc_4byte(uint32_t data, uint32_t init_val) > { > - return _mm_crc32_u32(init_val, data); > +#ifdef RTE_MACHINE_CPUFLAG_SSE4_2 > + if (likely(crc32_alg == CRC32_SSE42)) > + return _mm_crc32_u32(init_val, data); > +#endif you don't really need these ifdefs here anymore given that you have a constructor to do the algorithm selection. In fact you need to remove them, in the event you build on a system that doesn't support SSE42, but run on a system that does. Neil