From owner-svn-src-all@freebsd.org Wed Jul 8 18:29:03 2015 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 5F9F09957C8; Wed, 8 Jul 2015 18:29:03 +0000 (UTC) (envelope-from hiren@FreeBSD.org) Received: from mail.strugglingcoder.info (strugglingcoder.info [65.19.130.35]) (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 4D864164D; Wed, 8 Jul 2015 18:29:03 +0000 (UTC) (envelope-from hiren@FreeBSD.org) Received: from localhost (unknown [10.1.1.3]) (Authenticated sender: hiren@strugglingcoder.info) by mail.strugglingcoder.info (Postfix) with ESMTPSA id C27F7D2C48; Wed, 8 Jul 2015 11:29:01 -0700 (PDT) Date: Wed, 8 Jul 2015 11:29:01 -0700 From: hiren panchasara To: Alan Cox Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r285282 - head/sys/vm Message-ID: <20150708182901.GJ51988@strugglingcoder.info> References: <201507081746.t68Hk0To044278@repo.freebsd.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="451BZW+OUuJBCAYj" Content-Disposition: inline In-Reply-To: <201507081746.t68Hk0To044278@repo.freebsd.org> User-Agent: Mutt/1.5.23 (2014-03-12) X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.20 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, 08 Jul 2015 18:29:03 -0000 --451BZW+OUuJBCAYj Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 07/08/15 at 05:46P, Alan Cox wrote: > Author: alc > Date: Wed Jul 8 17:45:59 2015 > New Revision: 285282 > URL: https://svnweb.freebsd.org/changeset/base/285282 >=20 > Log: > The intention of r254304 was to scan the active queue continuously. > However, I've observed the active queue scan stopping when there are > frequent free page shortages and the inactive queue is steadily refilled > by other mechanisms, such as the sequential access heuristic in vm_faul= t() > or madvise(2).=20 What would be the actual downside/effect of this scenario? i.e. What goes wrong when active queue scan stops and what would I see/observe on a system when the problem is going on - is what I want to understand. > To remedy this problem, record the time of the last active > queue scan, and always scan a number of pages proportional to the time > since the last scan, regardless of whether that last scan was a > timeout-triggered ("pass =3D=3D 0") or free-page-shortage-triggered ("p= ass > > 0") scan. > =20 > Also, on a timeout-triggered scan, allow a full scan of the active queue > when the system is short of inactive pages. > =20 > Reviewed by: kib > MFC after: 6 weeks > Sponsored by: EMC / Isilon Storage Division [skip] Thanks in advance. Cheers, Hiren --451BZW+OUuJBCAYj Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (FreeBSD) iQF8BAEBCgBmBQJVnWvtXxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXRBNEUyMEZBMUQ4Nzg4RjNGMTdFNjZGMDI4 QjkyNTBFMTU2M0VERkU1AAoJEIuSUOFWPt/lNHYH+waL0+YG6SEy6g11jr2F3R2Y s4fxLWMlyY05g3Sdvluy3AWRBu0vMT/shQY//WfzrreaxpYXEfsL4428YYrtQ5m2 S8d50vNB6URdTaYTUleRCrzcg5/bzhb6yKPdI/9WWh7xzlBzUxv/+N3wh5KDRUD7 yiIRKoKCcVucDew0XClp/PDzsNjqQyRpHgDfYLv6fuCJh4e0ljowPgLu/3DC7xDy r/Z+Zf6SDzo6vwWXky3DSCXQuPR72HkX8jo8FDli44FrXFmXYaLKWCorLQSIVwGW pEeAe5XJkKh3M6LMCX5IFPrKIdeIeLBiWueciSCdUrwQFLC0keFGHx59sKzrIJg= =zQoP -----END PGP SIGNATURE----- --451BZW+OUuJBCAYj--