From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 64679 invoked by alias); 21 Mar 2017 05:15:03 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 64623 invoked by uid 89); 21 Mar 2017 05:15:01 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.4 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RCVD_IN_DNSWL_LOW autolearn=no version=3.3.2 spammy=academic, sheet X-HELO: mx0a-001b2d01.pphosted.com Subject: Re: [PATCH] powerpc64: strrchr optimization for power8 To: "Carlos O'Donell" , libc-alpha@sourceware.org References: <1487070321-27700-1-git-send-email-raji@linux.vnet.ibm.com> <52479e2b-f675-9d6e-7b34-27e24ee48081@redhat.com> <55dfbdb0-3776-caa9-e87b-10c297b4b496@linux.vnet.ibm.com> <139ea9b7-005d-fd33-a223-fe36fc995f4d@redhat.com> <00958c35-0b2d-60c9-f618-cfcd185710e8@linux.vnet.ibm.com> <5af3baaf-a340-cf07-10fc-f877d803dd6c@linux.vnet.ibm.com> <3e1454d4-ce03-f3a5-ac6f-6d9a7a0151f8@redhat.com> From: Rajalakshmi Srinivasaraghavan Date: Tue, 21 Mar 2017 05:15:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <3e1454d4-ce03-f3a5-ac6f-6d9a7a0151f8@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable x-cbid: 17032105-0012-0000-0000-000002205AB1 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17032105-0013-0000-0000-00000734B5BB Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-03-21_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1702020001 definitions=main-1703210047 X-SW-Source: 2017-03/txt/msg00453.txt.bz2 On 03/17/2017 09:08 PM, Carlos O'Donell wrote: > Knowing the mean value of string lengths would let us decide where > to place most of optimization efforts. I don't know that we have any > good references to academic literature here. > No, I dont have details about strrchr call statistics. This optimization is to make use of POWER 8 capabilties in general. > Now I plotted the power8 performance and there is a big bump in the middle, > any idea why? I could see some sudden increase for sizes 104-118 and around 222 in the shared sheet. However there is no special logic in the code related to these sizes. I tried to check if this happens on my test P8 ppc64le system and I could not recreate this. -- Thanks Rajalakshmi S