From owner-freebsd-current@FreeBSD.ORG Fri Mar 8 18:57:52 2013 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id D1904CD; Fri, 8 Mar 2013 18:57:52 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) by mx1.freebsd.org (Postfix) with ESMTP id 5F1771AD; Fri, 8 Mar 2013 18:57:52 +0000 (UTC) Received: from tom.home (kostik@localhost [127.0.0.1]) by kib.kiev.ua (8.14.6/8.14.6) with ESMTP id r28Ivk4T050654; Fri, 8 Mar 2013 20:57:46 +0200 (EET) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.8.0 kib.kiev.ua r28Ivk4T050654 Received: (from kostik@localhost) by tom.home (8.14.6/8.14.6/Submit) id r28Ivkwu050653; Fri, 8 Mar 2013 20:57:46 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Fri, 8 Mar 2013 20:57:45 +0200 From: Konstantin Belousov To: Andre Oppermann Subject: Re: Cleanup and untangling of kernel VM initialization Message-ID: <20130308185745.GV3794@kib.kiev.ua> References: <510BC24D.2090406@freebsd.org> <510BF6E0.8070007@rice.edu> <5138C877.9060808@freebsd.org> <20130308091634.GM3794@kib.kiev.ua> <5139E07E.4040704@freebsd.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="E/fydkOSwztHu2te" Content-Disposition: inline In-Reply-To: <5139E07E.4040704@freebsd.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on tom.home Cc: alc@freebsd.org, freebsd-current@freebsd.org, Alan Cox X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 08 Mar 2013 18:57:52 -0000 --E/fydkOSwztHu2te Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Mar 08, 2013 at 01:58:38PM +0100, Andre Oppermann wrote: > On 08.03.2013 10:16, Konstantin Belousov wrote: > > On Thu, Mar 07, 2013 at 06:03:51PM +0100, Andre Oppermann wrote: > >> pager_map: is used for pager IO to a storage media (disk). Not > >> pageable. Calculation: MAXPHYS * min(max(nbuf/4, 16), 256). > > > > It is more versatile. The space is used for pbufs, and pbufs currently > > also serve for physio, for the clustering, for aio needs. >=20 > Good to know. Isn't the ceiling of MAXPHYS * 256 a bit tight then? I doubt it. The ceiling on the amount of pbufs only limit the concurrency from the subsystems I enumerated. The pbuf allocations are sleepable (usually), so there is no correctness problem from having it sizes slightly lower then could be, and 256 parallel i/o's is good enough still. It might make sense to increase the pbuf KVA for arches with ample KVA, but it would only benefit special workloads which create lot of the concurrent i/o from the specific subsystems. E.g., the clustering cannot create more then 16MB of clusters for write, and with the default MAXPHYS of 128KB, this takes 64 pbufs. --E/fydkOSwztHu2te Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) iQIcBAEBAgAGBQJROjSpAAoJEJDCuSvBvK1BH7AP/3AkItM7Vjp41hoN8RZqSbr6 +r6P7IF0OFdCypPx6XQs/15lPOXiRQNRcuxdXfo9oQwxO0SrzIIzSP30DVKxx6ex jibatgv+LHMQlkACnQOyktKk9DVNgWzR7KT9sKg6fUtSTHZZCMLvz2z28quUGu/Q T+gTx4CWzNQk81JkuInRWMcJXEzVLjcgHp3JkGIXocwKVq2XX/LT14/28PwpVmy6 uMQQHpW/qK2IY/VpDFVflQTM+onVLO7CUJYNAesXXo1j18mKtab/ATXa9M9oxl6Q 4U4xu0wYEFBaBRSKGVoFn0MNwBaB1pOMrvaPO/lLVkug76WsXBlx0Bji7qX74E5l EMrSq+CVV3NUMPcQQDJIpEJ6ndZb9oRu4fq1jcGpFPFc1qzO8mf8XcrIusKvpSfe WZrF9wnrbsEwutYYQspdgJXxFKfuhRWWKMCHUq8wrFVEhp/b/oh+qCW/v0snsMmG /iHpK/ZM2pzfX3x+5ncnhRc5FPoAolvZ1gujlxoIik5glAkkT9VE1kkl2VwjXpiD E5z+Ti9ckOia7ooMwinjNGDy51UWGAz95bdFAUf+0BGJb3dLJQXO6l9OP2K2OGz9 rGb0tdPwJtx5Wz2Nk/QHURF1bcnqx2KHFe8Tn+BTs6wH3URv84xSK/gXZEesWJ8B oexvUUWf5NDNcMy9lM/k =0QHV -----END PGP SIGNATURE----- --E/fydkOSwztHu2te--