Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753796AbbLEPwH (ORCPT ); Sat, 5 Dec 2015 10:52:07 -0500 Received: from mail-qg0-f41.google.com ([209.85.192.41]:34321 "EHLO mail-qg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753315AbbLEPwF (ORCPT ); Sat, 5 Dec 2015 10:52:05 -0500 Subject: Re: [PATCH v2 00/13] MADV_FREE support To: Pavel Machek , Minchan Kim References: <1446600367-7976-1-git-send-email-minchan@kernel.org> <20151205111042.GA11598@amd> Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michael Kerrisk , linux-api@vger.kernel.org, Hugh Dickins , Johannes Weiner , Rik van Riel , Mel Gorman , KOSAKI Motohiro , Jason Evans , "Kirill A. Shutemov" , Shaohua Li , Michal Hocko , yalin.wang2010@gmail.com From: Daniel Micay Message-ID: <5663081E.4010205@gmail.com> Date: Sat, 5 Dec 2015 10:51:58 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: <20151205111042.GA11598@amd> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="25AEtqoWBXCvAxgbRSFnbrHf3lJq2GSlb" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2380 Lines: 55 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --25AEtqoWBXCvAxgbRSFnbrHf3lJq2GSlb Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 05/12/15 06:10 AM, Pavel Machek wrote: > On Wed 2015-11-04 10:25:54, Minchan Kim wrote: >> MADV_FREE is on linux-next so long time. The reason was two, I think. >> >> 1. MADV_FREE code on reclaim path was really mess. >=20 > Could you explain what MADV_FREE does? >=20 > Comment in code says 'free the page only when there's memory > pressure'. So I mark my caches MADV_FREE, no memory pressure, I can > keep using it? And if there's memory pressure, what happens? I get > zeros? SIGSEGV? You get zeroes. It's not designed for that use case right now. It's for malloc implementations to use internally. There would need to be a new feature like MADV_FREE_UNDO for it to be usable for caches and it may make more sense for that to be a separate feature entirely, i.e. have a different flag for marking too (not sure) since it wouldn't need to worry about whether stuff is touched. --25AEtqoWBXCvAxgbRSFnbrHf3lJq2GSlb Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJWYwgeAAoJEPnnEuWa9fIqgHIP/jTlp7FHHc0W2g6+GR5Httb2 2ORoNvgw05Ry1iOpPNIYOJJpUBz++nE6tDC57amsOLsV1/CKxw/kZDs+zSEeAIyR yQRIlG46pVA5nTmtpgBTGJX7ryD9BvDsoZKsWqkRJjby6S2Iy/v7c9bSjpmJdDVp 4hxrAgdBKWoSxnkcIC4LTEVGr9KhPEDyVXCihGhW78gMHY5KdnF4mxPPfgGaRTmq eths7pEK9aAEDB1mjXRNj1q7I/PV+2yNuwGl5Bgi1JuHVKx6fpjWH42C1CBdAxPD 8qEtaT18uJZcsO3yIp/J3caXLwYBNooQIFcDV/0HAYcGW1NjyJvoVvPdnXH+cVp2 ICBhOVMgRUVTQiAmxMXem5PS1nMMwTI3m1WmpShCNO0XI0kF5We4WhpeAt1wns+A mmLF3A/9JpdYwVnF4m7Sfj0lahSyvO+XJMJObtq5YwiAps/Cg91xC43rTe4n4TpK rhG0stTS/RlW6/vJYcF7K5eH4dzm3xPCOY1lOKG4xlfkDalO+rLfVz/CuUjDbDCK 4ut8JyO5eq9Wx3bG1h3/pHPrpgQOcrr7lNhrv+6259/dkzq5HQ5hl70bl8r1yZzJ 2EX35OxYYVrwIJVI8kovg9oyECXR4xAmz/KygYVCotJ4/0NNd/1792XCqyYvPvJ8 EL+l2snIELktLOqS2NSO =FiDs -----END PGP SIGNATURE----- --25AEtqoWBXCvAxgbRSFnbrHf3lJq2GSlb-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/