From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavan Nikhilesh Subject: Re: [PATCH] drivers: cleanup unnecessary global variables Date: Wed, 25 Apr 2018 21:22:00 +0530 Message-ID: <20180425155158.GA14975@ltp-pvn> References: <20180419185159.11266-1-pbhagavatula@caviumnetworks.com> <20180423090009.vpzv74r3uknh4jnx@platinum> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: dev@dpdk.org To: Olivier Matz , thomas@monjalon.net, jerin.jacob@caviumnetworks.com, hemant.agrawal@nxp.com, beilei.xing@intel.com, rasesh.mody@cavium.com, harish.patil@cavium.com, jianbo.liu@arm.com Return-path: Received: from NAM01-BN3-obe.outbound.protection.outlook.com (mail-bn3nam01on0070.outbound.protection.outlook.com [104.47.33.70]) by dpdk.org (Postfix) with ESMTP id 2E3568DA1 for ; Wed, 25 Apr 2018 17:52:19 +0200 (CEST) Content-Disposition: inline In-Reply-To: <20180423090009.vpzv74r3uknh4jnx@platinum> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Mon, Apr 23, 2018 at 11:00:09AM +0200, Olivier Matz wrote: > On Fri, Apr 20, 2018 at 12:21:59AM +0530, Pavan Nikhilesh wrote: > > Signed-off-by: Pavan Nikhilesh > > --- > > drivers/bus/dpaa/base/fman/netcfg_layer.c | 5 ----- > > drivers/bus/dpaa/base/qbman/bman_driver.c | 4 ++-- > > drivers/bus/dpaa/base/qbman/qman.c | 2 +- > > drivers/bus/dpaa/base/qbman/qman_driver.c | 4 ++-- > > drivers/bus/dpaa/base/qbman/qman_priv.h | 1 - > > drivers/bus/dpaa/dpaa_bus.c | 2 +- > > drivers/bus/fslmc/qbman/qbman_portal.c | 3 +-- > > drivers/bus/fslmc/qbman/qbman_portal.h | 1 - > > drivers/net/i40e/i40e_flow.c | 2 +- > > drivers/net/qede/base/bcm_osal.c | 2 +- > > drivers/raw/skeleton_rawdev/skeleton_rawdev.c | 2 +- > > lib/librte_net/net_crc_neon.h | 4 ++-- > > 12 files changed, 12 insertions(+), 20 deletions(-) > > [...] > > > diff --git a/lib/librte_net/net_crc_neon.h b/lib/librte_net/net_crc_neon.h > > index 63fa1d4a1..cb3da72ed 100644 > > --- a/lib/librte_net/net_crc_neon.h > > +++ b/lib/librte_net/net_crc_neon.h > > @@ -21,8 +21,8 @@ struct crc_pmull_ctx { > > uint64x2_t rk7_rk8; > > }; > > > > -struct crc_pmull_ctx crc32_eth_pmull __rte_aligned(16); > > -struct crc_pmull_ctx crc16_ccitt_pmull __rte_aligned(16); > > +static struct crc_pmull_ctx crc32_eth_pmull __rte_aligned(16); > > +static struct crc_pmull_ctx crc16_ccitt_pmull __rte_aligned(16); > > > > /** > > Not sure it will still work after that. > > From what I see, these global variables are initialized once in > rte_net_crc_neon_init, and used as a const parameter in > crc32_eth_calc_pmull(). > > Changing them to static will create an instance of these variables for > each included file, which is not what we want. > > I think that the proper way to solve it would be to add the definition > in a new .c file, and only have a declaration in the .h. > > Hi Olivier, Thanks for the heads up, the second solution seems more viable and while implementing it I faced few Issues. GCC doesnt suport const vector instructions i.e. the following assignment throw as compiler error. static const struct crc_pmull_ctx crc32_eth_pmull = { .rk1_rk2 = vld1q_u64((uint64_t[2]){0xccaa009eLLU, 0x1751997d0LLU}), .rk5_rk6 = vld1q_u64((uint64_t[2]){0xccaa009eLLU, 0x163cd6124LLU}), .rk7_rk8 = vld1q_u64((uint64_t[2]){0x1f7011640LLU, 0x1db710641LLU}), } __rte_aligned(16); I have gotten path the error by modifying struct crc_pmull_ctx as follows: struct crc_pmull_ctx { union { uint64_t rk12[2]; uint64x2_t rk1_rk2; }; union { uint64_t rk56[2]; uint64x2_t rk5_rk6; }; union { uint64_t rk78[2]; uint64x2_t rk7_rk8; }; }; static const struct crc_pmull_ctx crc32_eth_pmull __rte_aligned(16) = { .rk12 = {0xccaa009eLLU, 0x1751997d0LLU}, .rk56 = {0xccaa009eLLU, 0x163cd6124LLU}, .rk78 = {0x1f7011640LLU, 0x1db710641LLU}, }; static const struct crc_pmull_ctx crc16_ccitt_pmull __rte_aligned(16) = { .rk12 = {0x189aeLLU, 0x8e10LLU}, .rk56 = {0x189aeLLU, 0x114aaLLU}, .rk78 = {0x11c581910LLU, 0x10811LLU}, }; I have checked the hex dump of the assignment with the current code and the above piece of code and they are similar. Let me know if my solution seems viable I will send the v2. > An even better way would be to make variable const and initialize it > with its content. It could even enhance performance. Something like: > > net_crc_neon.h: > > static const struct crc_pmull_ctx crc32_eth_pmull = { > > } __rte_aligned(16); > > static const struct crc_pmull_ctx crc16_ccitt_pmull = { > > } __rte_aligned(16); > Thanks, Pavan.