[{"id":1771839,"web_url":"http://patchwork.ozlabs.org/comment/1771839/","msgid":"<59C26B1F.7090801@arm.com>","list_archive_url":null,"date":"2017-09-20T13:20:31","subject":"Re: [PATCH 5/9] New generic log2f","submitter":{"id":65667,"url":"http://patchwork.ozlabs.org/api/people/65667/","name":"Szabolcs Nagy","email":"szabolcs.nagy@arm.com"},"content":"On 19/09/17 14:00, Szabolcs Nagy wrote:\n> Similar to the new logf: double precision arithmetics\n> and a small lookup table is used. The argument reduction\n> step is the same as for the new logf.\n> \n> with naive ubenchmark (on aarch64):\n> reciprocal-throughput: 2.7x faster\n> latency: 2x faster\n\nwith the committed log2f benchmark it's\n\nreciprocal-throughput: 2.3x faster\nlatency: 2.1x faster\n\n> old worst case error: 1.72 ulp\n> new worst case error: 0.75 ulp\n> aarch64 .text size: -252 bytes\n> aarch64 .rodata size: +244 bytes\n> \n> 2017-09-19 Szabolcs Nagy \n> \n> \t* math/Makefile (type-float-routines): Add e_log2f_data.\n> \t* sysdeps/ieee754/flt-32/e_log2f.c: New implementation.\n> \t* sysdeps/ieee754/flt-32/e_log2f_data.c: New file.\n> \t* sysdeps/ieee754/flt-32/math_config.h (__log2f_data): Define.\n> \t(LOG2F_TABLE_BITS, LOG2F_POLY_ORDER): Define.\n> \t* sysdeps/i386/fpu/e_log2f_data.c: New file.\n> \t* sysdeps/ia64/fpu/e_log2f_data.c: New file.\n> \t* sysdeps/m68k/m680x0/fpu/e_log2f_data.c: New file.\n>","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":["patchwork-incoming@bilbo.ozlabs.org","mailing list libc-alpha@sourceware.org"],"Authentication-Results":["ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=sourceware.org\n\t(client-ip=209.132.180.131; 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Linux x86_64;\n\trv:31.0) Gecko/20100101 Thunderbird/31.8.0","MIME-Version":"1.0","To":"GNU C Library ","CC":"nd@arm.com","Subject":"Re: [PATCH 5/9] New generic log2f","References":"<59C1123F.9080003@arm.com> <59C114D5.5090009@arm.com>","In-Reply-To":"<59C114D5.5090009@arm.com>","Content-Type":"text/plain; charset=utf-8","Content-Transfer-Encoding":"7bit","X-ClientProxiedBy":"AM5PR0102CA0012.eurprd01.prod.exchangelabs.com\n\t(2603:10a6:206::25) To VI1PR0802MB2493.eurprd08.prod.outlook.com\n\t(2603:10a6:800:b4::23)","X-MS-PublicTrafficType":"Email","X-MS-Office365-Filtering-Correlation-Id":"c6773a39-27b6-411e-57d7-08d5002a60a0","X-MS-Office365-Filtering-HT":"Tenant","X-Microsoft-Antispam":"UriScan:; BCL:0; PCL:0;\n\tRULEID:(300000500095)(300135000095)(300000501095)(300135300095)(22001)(300000502095)(300135100095)(2017030254152)(48565401081)(300000503095)(300135400095)(201703131423075)(201703031133081)(201702281549075)(300000504095)(300135200095)(300000505095)(300135600095)(300000506095)(300135500095);\n\tSRVR:VI1PR0802MB2493; 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