From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by dpdk.org (Postfix) with ESMTP id 10CE18D97 for ; Mon, 18 Jan 2016 15:25:24 +0100 (CET) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga102.jf.intel.com with ESMTP; 18 Jan 2016 06:25:24 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,312,1449561600"; d="scan'208";a="893020282" Received: from sie-lab-214-036.ir.intel.com (HELO sie-lab-214-174.ir.intel.com) ([10.237.214.36]) by orsmga002.jf.intel.com with ESMTP; 18 Jan 2016 06:25:23 -0800 From: Pablo de Lara To: bombermag@gmail.com Date: Mon, 18 Jan 2016 14:25:20 +0000 Message-Id: <1453127120-38068-1-git-send-email-pablo.de.lara.guarch@intel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: References: Cc: users@dpdk.org Subject: Re: [dpdk-users] Broken hash table functions with CFLAGS -O3 X-BeenThere: users@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: usage discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 18 Jan 2016 14:25:25 -0000 > -----Original Message----- > From: users [mailto:users-bounces@dpdk.org] On Behalf Of Dmitriy Yakovlev > Sent: Friday, January 15, 2016 1:20 AM > To: users@dpdk.org > Subject: [dpdk-users] Broken hash table functions with CFLAGS -O3 > > Hello. > I trying to use hash tables for adding struct ip:port as key. > When trying to add duplicated key it's successfuly added second time, not > always, but sometimes. > Please see this youtube video, where I'm demonstrating this bug: > https://www.youtube.com/watch?v=vsXVxISpmnU > Code on github: https://github.com/BombermaG/bug-app > > When using CFLAGS -O2 this problem cannot be repeated. > It's problem with -O3 flag and I must use O2 or how can I solve it? > Thank you for helping. > (Sorry if this message double posting). > > Spec info. Tell me, if you need more info. > dpdk 2.2.0 Hello Dmitriy, Thanks for the detailed report. I am able to reproduce the issue with gcc 4.7 and 4.8. The problem is that the signature sometimes changes, due to a different key and therefore the bucket where it should be stored is the wrong one. Actually, the hash table is fine. The issue is that your key is a structure of a 4-byte and 2-byte integers, so your key size should be 6, but instead, it is 8, because sizeof(struct...) includes padding to have it multiple of 4. Most times, that padding is 0, so it is fine, but when that padding is not 0, the key is different and then it looks like you are adding a duplicate (but actually you are adding a different key!). So, either add padding manually in the key or manually set the key size to 6. Regards, Pablo > > Linux 3.10.0-229.el7.x86_64 #1 SMP Fri Mar 6 11:36:42 UTC 2015 x86_64 > x86_64 x86_64 GNU/Linux > > gcc -v > Using built-in specs. > COLLECT_GCC=gcc > COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.8.5/lto-wrapper > Target: x86_64-redhat-linux > Configured with: ../configure --prefix=/usr --mandir=/usr/share/man -- > infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla > --enable-bootstrap --enable-shared --enable-threads=posix --enable- > checking=release --with-system-zlib --enable-__cxa_atexit --disable- > libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id - > -with-linker-hash-style=gnu --enable-languages=c,c++,objc,obj- > c++,java,fortran,ada,go,lto > --enable-plugin --enable-initfini-array --disable-libgcj --with- > isl=/builddir/build/BUILD/gcc-4.8.5-20150702/obj-x86_64-redhat-linux/isl- > install > --with-cloog=/builddir/build/BUILD/gcc-4.8.5-20150702/obj-x86_64-redhat- > linux/cloog-install > --enable-gnu-indirect-function --with-tune=generic --with-arch_32=x86-64 - > -build=x86_64-redhat-linux Thread model: posix gcc version 4.8.5 20150623 > (Red Hat 4.8.5-4) (GCC) > > Intel(R) Xeon(R) CPU E5-2643 v2 @ 3.50GHz