From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by sourceware.org (Postfix) with ESMTPS id ADBE4383F843 for ; Mon, 22 Jun 2020 13:59:14 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org ADBE4383F843 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 05MDsW4o015197; Mon, 22 Jun 2020 09:59:11 -0400 Received: from ppma02wdc.us.ibm.com (aa.5b.37a9.ip4.static.sl-reverse.com [169.55.91.170]) by mx0a-001b2d01.pphosted.com with ESMTP id 31submuppy-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 22 Jun 2020 09:59:11 -0400 Received: from pps.filterd (ppma02wdc.us.ibm.com [127.0.0.1]) by ppma02wdc.us.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 05MDu34B012572; Mon, 22 Jun 2020 13:59:09 GMT Received: from b03cxnp08026.gho.boulder.ibm.com (b03cxnp08026.gho.boulder.ibm.com [9.17.130.18]) by ppma02wdc.us.ibm.com with ESMTP id 31sa38qytn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 22 Jun 2020 13:59:09 +0000 Received: from b03ledav006.gho.boulder.ibm.com (b03ledav006.gho.boulder.ibm.com [9.17.130.237]) by b03cxnp08026.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 05MDx64A30998816 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 22 Jun 2020 13:59:06 GMT Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C020BC605D; Mon, 22 Jun 2020 13:59:08 +0000 (GMT) Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 991FCC6055; Mon, 22 Jun 2020 13:59:08 +0000 (GMT) Received: from [9.163.88.97] (unknown [9.163.88.97]) by b03ledav006.gho.boulder.ibm.com (Postfix) with ESMTP; Mon, 22 Jun 2020 13:59:08 +0000 (GMT) Subject: Re: faster expf128 To: Paul Zimmermann , libc-alpha@sourceware.org References: From: Paul E Murphy Message-ID: Date: Mon, 22 Jun 2020 08:59:08 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216, 18.0.687 definitions=2020-06-22_07:2020-06-22, 2020-06-22 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 impostorscore=0 suspectscore=0 mlxlogscore=491 cotscore=-2147483648 mlxscore=0 adultscore=0 phishscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 malwarescore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006220098 X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, KAM_NUMSUBJECT, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 22 Jun 2020 13:59:15 -0000 On 6/22/20 6:02 AM, Paul Zimmermann wrote: > I have written some expf128 for x86_64 that is more than 10 times faster than > the current glibc/libquadmath code [1] (see slide 21 of [2]). I would highly recommend running the benchmarks against ppc64le or s390x before replacing the existing implementation. I think it would improve the code to have more explicit separation between implementations optimized for soft and hardfp if performance cannot be rectified. I think much of the float128 support assumes the underlying machine does not natively support binary128. > > Before making a proper patch for glibc, I'd like to make sure it fits the > glibc requirements. In particular, the table size is 16kb. Is that ok? > If too large, what table size would be ok? I think that is acceptable. The current tables for expf128 probably aren't much smaller, if I recall correctly.