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 E06AB7EB0 for ; Tue, 18 Nov 2014 18:36:07 +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 1Xqmr7-00056P-0D; Tue, 18 Nov 2014 12:46:23 -0500 Date: Tue, 18 Nov 2014 12:46:19 -0500 From: Neil Horman To: Yerden Zhumabekov Message-ID: <20141118174619.GE32375@hmsreliant.think-freely.org> 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> <546B7E2D.7050705@sts.kz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <546B7E2D.7050705@sts.kz> 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 17:36:08 -0000 On Tue, Nov 18, 2014 at 11:13:17PM +0600, Yerden Zhumabekov wrote: > > 18.11.2014 22:00, Neil Horman пишет: > > On Tue, Nov 18, 2014 at 09:06:35PM +0600, Yerden Zhumabekov wrote: > >> 18.11.2014 20:41, Neil Horman пишет: > >>> 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. > >>>> + * 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. > >> Originally, I thought so as well. I wrote the code without these ifdefs, > >> but it didn't compile on my machine which doesn't support SSE4.2. Error > >> 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 option > > -msse42. That way it will know to emit sse42 instructions. It will also 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? :) > Crud, you're right, I didn't think about the header inclusion issue. Is it worth adding the jump to enable the dynamic hash selection? Neil > -- > Sincerely, > > Yerden Zhumabekov > State Technical Service > Astana, KZ > > >