From owner-svn-src-all@freebsd.org Fri May 3 02:55:55 2019 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 2AEB71581F22; Fri, 3 May 2019 02:55:55 +0000 (UTC) (envelope-from dougm@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id C53E183D98; Fri, 3 May 2019 02:55:54 +0000 (UTC) (envelope-from dougm@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 9E0711A9AB; Fri, 3 May 2019 02:55:54 +0000 (UTC) (envelope-from dougm@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x432tsNL001163; Fri, 3 May 2019 02:55:54 GMT (envelope-from dougm@FreeBSD.org) Received: (from dougm@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x432tsKK001162; Fri, 3 May 2019 02:55:54 GMT (envelope-from dougm@FreeBSD.org) Message-Id: <201905030255.x432tsKK001162@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: dougm set sender to dougm@FreeBSD.org using -f From: Douglas William Moore Date: Fri, 3 May 2019 02:55:54 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r347043 - head/sys/vm X-SVN-Group: head X-SVN-Commit-Author: dougm X-SVN-Commit-Paths: head/sys/vm X-SVN-Commit-Revision: 347043 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: C53E183D98 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.97 / 15.00]; local_wl_from(0.00)[FreeBSD.org]; NEURAL_HAM_MEDIUM(-1.00)[-0.999,0]; NEURAL_HAM_SHORT(-0.97)[-0.972,0]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US]; NEURAL_HAM_LONG(-1.00)[-1.000,0] X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 03 May 2019 02:55:55 -0000 Author: dougm Date: Fri May 3 02:55:54 2019 New Revision: 347043 URL: https://svnweb.freebsd.org/changeset/base/347043 Log: fls() should find the most significant bit of an int faster than a linear search can, so use it to avoid a linear search in isqrt. Approved by: kib (mentor), markj (mentor) Differential Revision: https://reviews.freebsd.org/D20102 Modified: head/sys/vm/vm_pageout.c Modified: head/sys/vm/vm_pageout.c ============================================================================== --- head/sys/vm/vm_pageout.c Fri May 3 02:51:33 2019 (r347042) +++ head/sys/vm/vm_pageout.c Fri May 3 02:55:54 2019 (r347043) @@ -928,9 +928,7 @@ isqrt(u_int num) { u_int bit, root, tmp; - bit = 1u << ((NBBY * sizeof(u_int)) - 2); - while (bit > num) - bit >>= 2; + bit = num != 0 ? (1u << ((fls(num) - 1) & ~1)) : 0; root = 0; while (bit != 0) { tmp = root + bit;