From owner-freebsd-hackers Fri Jan 3 4:17:28 2003 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 618F037B401 for ; Fri, 3 Jan 2003 04:17:26 -0800 (PST) Received: from host2.rila.bg (host2.rila.bg [62.73.64.21]) by mx1.FreeBSD.org (Postfix) with ESMTP id 92C5C43EA9 for ; Fri, 3 Jan 2003 04:17:19 -0800 (PST) (envelope-from Dimitar.Peikov@rila.com) Received: from mobilin.rila.bg ([192.168.201.78]) by host2.rila.bg with Microsoft SMTPSVC(5.0.2195.5329); Fri, 3 Jan 2003 14:17:05 +0200 Received: from mobilin.rila.bg (localhost [127.0.0.1]) by mobilin.rila.bg (8.12.2/8.12.2/SuSE Linux 0.6) with ESMTP id h03DJOqa008144 for ; Fri, 3 Jan 2003 15:19:24 +0200 Received: from localhost (localhost [[UNIX: localhost]]) by mobilin.rila.bg (8.12.2/8.12.2/Submit) id h03DJNH6008143 for freebsd-hackers@freebsd.org; Fri, 3 Jan 2003 15:19:23 +0200 Content-Type: text/plain; charset="utf-8" From: Dimitar Peikov Reply-To: mitko@rila.bg Organization: RILA Solutions To: freebsd-hackers@freebsd.org Subject: bzero() in mfs_doio() Date: Fri, 3 Jan 2003 15:19:19 +0200 X-Mailer: KMail [version 1.4] MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Message-Id: <200301031519.22540.mitko@rila.bg> X-OriginalArrivalTime: 03 Jan 2003 12:17:05.0825 (UTC) FILETIME=[07A41910:01C2B322] Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi, I've read some part of the UFS/MFS code and saw the bzero() in code, but=20 according the madvice() manual page for MADV_FREE, this step is not neede= d. Also frequent calls to mfs_doio() causes serious performance penalty, am = I=20 right? >>>>>> MADV_FREE Gives the VM system the freedom to free pages, and = tells the system that information in the specified page r= ange is no longer important. This is an efficient way o= f allowing malloc(3) to free pages anywhere in the ad= dress space, while keeping the address space valid. The = next time that the page is referenced, the page might be demand zeroed, or might contain the data that was t= here before the MADV_FREE call. References made to that address space range will not make the VM system pag= e the information back in from backing store until the pa= ge is modified again. >>>>>> /sys/ufs/mfs/mfs_vnops.c:259 >>>>>> =09=09=09bytes &=3D ~PAGE_MASK; =09=09=09if (bytes !=3D 0) { =09=09=09=09bzero(&uap, sizeof(uap)); =09=09=09=09uap.addr =3D base; =09=09=09=09uap.len =3D bytes; =09=09=09=09uap.behav =3D MADV_FREE; =09=09=09=09madvise(curproc, &uap); =09=09=09} >>>>>> =20 - --=20 Dimitar Peikov Programmer Analyst Globalization Group "We Build e-Business" =20 RILA Solutions =20 27 Building, Acad.G.Bonchev Str. =20 1113 Sofia, Bulgaria =20 phone: (+359 2) 9797320=20 phone: (+359 2) 9797300=20 fax: (+359 2) 9733355 =20 http://www.rila.com=20 GnuPG key http://earth.rila.bg/~mitko/mitko.key.asc GnuPG key http://www.bgzone.com/~mitko/mitko.key.asc Key fingerprint 97AF 6192 78E2 AC68 FD56 CCB0 68B9 DF7D B3C1 9ED7 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE+FY3aaLnffbPBntcRAjdmAJ9TJRugyEn243W2nfX1QKNdY1yc5QCdGwqs 1TGC/1b9xgJuofP6js/u7p0=3D =3D6zCO -----END PGP SIGNATURE----- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message