From owner-svn-src-all@freebsd.org Wed Dec 14 23:36:33 2016 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id E6D0AC800C1; Wed, 14 Dec 2016 23:36:33 +0000 (UTC) (envelope-from kib@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 mx1.freebsd.org (Postfix) with ESMTPS id B69C56D6; Wed, 14 Dec 2016 23:36:33 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id uBENaWo8076904; Wed, 14 Dec 2016 23:36:32 GMT (envelope-from kib@FreeBSD.org) Received: (from kib@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id uBENaWX7076903; Wed, 14 Dec 2016 23:36:32 GMT (envelope-from kib@FreeBSD.org) Message-Id: <201612142336.uBENaWX7076903@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: kib set sender to kib@FreeBSD.org using -f From: Konstantin Belousov Date: Wed, 14 Dec 2016 23:36:32 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r310098 - head/sys/vm X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.23 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: Wed, 14 Dec 2016 23:36:34 -0000 Author: kib Date: Wed Dec 14 23:36:32 2016 New Revision: 310098 URL: https://svnweb.freebsd.org/changeset/base/310098 Log: Provide introductory description of the default pager. Reviewed by: alc Sponsored by: The FreeBSD Foundation MFC after: 1 week Modified: head/sys/vm/default_pager.c Modified: head/sys/vm/default_pager.c ============================================================================== --- head/sys/vm/default_pager.c Wed Dec 14 23:34:25 2016 (r310097) +++ head/sys/vm/default_pager.c Wed Dec 14 23:36:32 2016 (r310098) @@ -57,6 +57,16 @@ static boolean_t default_pager_haspage(v /* * pagerops for OBJT_DEFAULT - "default pager". + * + * This pager handles anonymous (no handle) swap-backed memory, just + * like the swap pager. It allows several optimizations based on the + * fact that no pages of a default object can be swapped out. The + * most important optimization is in vm_fault(), where the pager is + * never asked for a non-resident page. Instead, a freshly allocated + * zeroed page is used. + * + * On the first request to page out a page from a default object, the + * object is converted to swap pager type. */ struct pagerops defaultpagerops = { .pgo_alloc = default_pager_alloc,