From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id 13D6C388C03D for ; Thu, 6 May 2021 16:42:37 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 13D6C388C03D Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-491-RDYlsSFsNlm8Ey9dKgPq3g-1; Thu, 06 May 2021 12:42:33 -0400 X-MC-Unique: RDYlsSFsNlm8Ey9dKgPq3g-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4BAA91922962; Thu, 6 May 2021 16:42:32 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-137.ams2.redhat.com [10.36.112.137]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C5FBA19D9F; Thu, 6 May 2021 16:42:30 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella Cc: Paul Eggert , Adhemerval Zanella via Libc-alpha , crrodriguez@opensuse.org Subject: Re: [PATCH 1/4] Remove architecture specific sched_cpucount optimizations References: <20210329182520.323665-1-adhemerval.zanella@linaro.org> <87a6p9dr9n.fsf@oldenburg.str.redhat.com> <61040ff8-caac-a3d9-91cc-9b445c4e98fd@cs.ucla.edu> <87pmy4gepw.fsf@oldenburg.str.redhat.com> <9a0723f4-82ec-ae41-0304-3dc1af0bb2c0@linaro.org> Date: Thu, 06 May 2021 18:42:49 +0200 In-Reply-To: <9a0723f4-82ec-ae41-0304-3dc1af0bb2c0@linaro.org> (Adhemerval Zanella's message of "Thu, 6 May 2021 13:16:39 -0300") Message-ID: <87wnsbg6eu.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, 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: Thu, 06 May 2021 16:42:38 -0000 * Adhemerval Zanella: >> I get that choosing the exact matching builtin for the __cpu_mask type >> isn't easy, but wouldn't it be safe to use __builtin_popcountll >> unconditionally? > > Using a open-coded routine is slight better for architectures that > do not have a popcount instruction, since __builtin_popcountll will > call the libgcc routine). But I hardly think we need that amount > of micro-optimization for such routine. Ahh, and we'll get a check-localplt failure. Hmm. So mention that in the comment? Thanks, Florian