From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yerden Zhumabekov Subject: Re: [PATCH v4 3/5] hash: add fallback to software CRC32 implementation Date: Tue, 18 Nov 2014 23:13:17 +0600 Message-ID: <546B7E2D.7050705@sts.kz> References: <1409724351-23786-1-git-send-email-e_zhumabekov@sts.kz> <20141118144138.GB32375@hmsreliant.think-freely.org> <546B607B.9030808@sts.kz> <20141118160005.GC32375@hmsreliant.think-freely.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable To: Neil Horman , "Richardson, Bruce" , "dev-VfR2kkLFssw@public.gmane.org" Return-path: In-Reply-To: <20141118160005.GC32375-B26myB8xz7F8NnZeBjwnZQMhkBWG/bsMQH7oEaQurus@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" 18.11.2014 22:00, Neil Horman =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > On Tue, Nov 18, 2014 at 09:06:35PM +0600, Yerden Zhumabekov wrote: >> 18.11.2014 20:41, Neil Horman =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>> On Tue, Nov 18, 2014 at 08:03:40PM +0600, Yerden Zhumabekov wrote: >>>> /** >>>> * Use single crc32 instruction to perform a hash on a 4 byte value= =2E >>>> + * 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 =3D=3D 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 remov= e them, in >>> the event you build on a system that doesn't support SSE42, but run o= n a system >>> that does. >> Originally, I thought so as well. I wrote the code without these ifdef= s, >> but it didn't compile on my machine which doesn't support SSE4.2. Erro= r >> was triggered by nmmintrin.h which has a check for respective GCC >> extension. So I think these ifdefs are indeed required. >> > You need to edit the makefile so that the compiler gets passed the opti= on > -msse42. That way it will know to emit sse42 instructions. It will als= o allow > you to remove the ifdef from the include file In this case, I guess there are two options: 1) modify all makefiles which use librte_hash 2) move all function bodies from rte_hash_crc.h to separate module, leaving prototype definitions there only. Everybody's up for the second option? :) --=20 Sincerely, Yerden Zhumabekov State Technical Service Astana, KZ