From owner-cvs-src@FreeBSD.ORG Tue Mar 20 03:44:11 2007 Return-Path: X-Original-To: cvs-src@FreeBSD.org Delivered-To: cvs-src@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 78FF816A402; Tue, 20 Mar 2007 03:44:11 +0000 (UTC) (envelope-from jasone@FreeBSD.org) Received: from repoman.freebsd.org (repoman.freebsd.org [69.147.83.41]) by mx1.freebsd.org (Postfix) with ESMTP id 66CC313C459; Tue, 20 Mar 2007 03:44:11 +0000 (UTC) (envelope-from jasone@FreeBSD.org) Received: from repoman.freebsd.org (localhost [127.0.0.1]) by repoman.freebsd.org (8.13.8/8.13.8) with ESMTP id l2K3iBDO029450; Tue, 20 Mar 2007 03:44:11 GMT (envelope-from jasone@repoman.freebsd.org) Received: (from jasone@localhost) by repoman.freebsd.org (8.13.8/8.13.8/Submit) id l2K3iBlg029449; Tue, 20 Mar 2007 03:44:11 GMT (envelope-from jasone) Message-Id: <200703200344.l2K3iBlg029449@repoman.freebsd.org> From: Jason Evans Date: Tue, 20 Mar 2007 03:44:11 +0000 (UTC) To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org X-FreeBSD-CVS-Branch: HEAD Cc: Subject: cvs commit: src/lib/libc/stdlib malloc.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 20 Mar 2007 03:44:11 -0000 jasone 2007-03-20 03:44:10 UTC FreeBSD src repository Modified files: lib/libc/stdlib malloc.c Log: Avoid using vsnprintf(3) unless MALLOC_STATS is defined, in order to avoid substantial potential bloat for static binaries that do not otherwise use any printf(3)-family functions. [1] Rearrange arena_run_t so that the region bitmask can be minimally sized according to constraints related to each bin's size class. Previously, the region bitmask was the same size for all run headers, which wasted a measurable amount of memory. Rather than making runs for small objects as large as possible, make runs as small as possible such that header overhead stays below a certain bound. There are two exceptions that override the header overhead bound: 1) If the bound is impossible to honor, it is relaxed on a per-size-class basis. Since there is one bit of header overhead per object (plus a constant), it is impossible to achieve a header overhead less than or equal to 1/(# of bits per object). For the current setting of maximum 0.5% header overhead, this relaxation comes into play for {2, 4, 8, 16}-byte objects, for which header overhead is (on 64-bit systems) {7.1, 4.3, 2.2, 1.2}%, respectively. 2) There is still a cap on small run size, still set to 64kB. This comes into play for {1024, 2048}-byte objects, for which header overhead is {1.6, 3.1}%, respectively. In practice, this reduces the run sizes, which makes worst case low-water memory usage due to fragmentation less bad. It also reduces worst case high-water run fragmentation due to non-full runs, but this is only a constant improvement (most important to small short-lived processes). Reduce the default chunk size from 2MB to 1MB. Benchmarks indicate that the external fragmentation reduction makes 1MB the new sweet spot (as small as possible without adversely affecting performance). Reported by: [1] kientzle Revision Changes Path 1.141 +235 -154 src/lib/libc/stdlib/malloc.c