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Bruce Fields" , Arnd Bergmann , Richard Henderson , Ivan Kokshaysky , Matt Turner , "James E.J. Bottomley" , Helge Deller , "David S. Miller" , Jakub Kicinski , "Eric Dumazet" , David Laight , "linux-fsdevel@vger.kernel.org" , "linux-arch@vger.kernel.org" , "linux-alpha@vger.kernel.org" , "linux-parisc@vger.kernel.org" , "sparclinux@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Changli Gao Subject: RE: [PATCH v2] Implement close-on-fork Thread-Topic: [PATCH v2] Implement close-on-fork Thread-Index: AQHWKtJnQW28Wposd0uF0sb7I7R5yaipUEHg Date: Fri, 15 May 2020 16:26:28 +0000 Message-ID: <954ef5ce2e47472f8b41300bf59209c5@garmin.com> References: <20200515152321.9280-1-nate.karstens@garmin.com> <20200515160342.GE23230@ZenIV.linux.org.uk> In-Reply-To: <20200515160342.GE23230@ZenIV.linux.org.uk> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.50.4.7] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-TM-AS-Product-Ver: SMEX-12.5.0.1300-8.5.1020-25422.001 X-TM-AS-Result: No-25.565400-8.000000-10 X-TMASE-MatchedRID: IDdx3MBO6EA4lC5Kv9wUbvGSfx66m+aMOxjb9QQbt+RjjMm9SMavFeSZ sOHi07gEr/8sDK1kxPbQa1VnD/+FPUvOGeNuCS0S9FQh3flUIh7lEwMU8A2NKG0emrRhsFGLH9B pMenWNIoWh4Aghj5bPYFHACWsU4r1gQDUCAaEDqmdVNZaI2n6/+lUxvXGcRIyuIuOQRFsnGiD/m A2vw4bvUBcp7vyblpbpr6zm+W2pl9RBKsfa1kPYQPZZctd3P4Ba2pCAnJvQFEcNByoSo036QjyL z97jpWXx5s4kxOoTl8gns2A4NkG5uE1n7m+jMjAiVJZi91I9Jh6cSMyMC0ZbueB6sW/fZnmiqr8 0tignQ46GiPP4hQJxbqJ0tfeyPe1R/LrKX7ntfC+vuhCHYf164IA1xEih5kwVOFdaTLzUEenyTA 2OWm+MsvuusssvZ6cxv0KARCYxbkmiAtJc/lr9+yNEc7z2JzCyBEE5Ydf0DFemWwoCXDj9WkCNf w/mPvvYWE02nN6lGcqrrWA7JXyB0GpYFFdx/uzttAWxuM5sl7uHZGuwo6K7bkrYtQaB6j21ddNq 6Z3NmdzIPtgA8AbFVaHG9BGTPOGKdJFmt/C31gmxe9I4Ere+oBOBQVQ0d5DpdltGKiWi0WoB03w QCIXjuRGNnMG86C8Iaqr32MlVaUT1tvBsmDmruCdOJAyA+r+42To+uHNEPbN+Vkq4CuVk6PFjJE Fr+olhAvhah9RwybYDKq9BLK39+JGF26G8SWy5yM0c1ktj9M= X-TM-AS-User-Approved-Sender: No X-TM-AS-User-Blocked-Sender: No X-TMASE-Result: 10--25.565400-8.000000 X-TMASE-Version: SMEX-12.5.0.1300-8.5.1020-25422.001 X-EOPAttributedMessage: 0 X-MS-Office365-Filtering-HT: Tenant X-Forefront-Antispam-Report: CIP:204.77.163.244;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:edgetransport.garmin.com;PTR:extedge.garmin.com;CAT:NONE;SFTY:;SFS:(39860400002)(376002)(136003)(396003)(346002)(46966005)(26005)(186003)(8676002)(82310400002)(7696005)(316002)(24736004)(7636003)(6916009)(108616005)(7416002)(82740400003)(54906003)(8936002)(356005)(2906002)(47076004)(86362001)(16799955002)(70586007)(70206006)(2616005)(53546011)(336012)(36756003)(5660300002)(478600001)(966005)(426003)(4326008);DIR:OUT;SFP:1102; X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 15467618-325c-40ce-2458-08d7f8ecb952 X-MS-TrafficTypeDiagnostic: DM6PR04MB4793: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:10000; X-Forefront-PRVS: 04041A2886 X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-OriginatorOrg: garmin.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 May 2020 16:26:30.0243 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 15467618-325c-40ce-2458-08d7f8ecb952 X-MS-Exchange-CrossTenant-Id: 38d0d425-ba52-4c0a-a03e-2a65c8e82e2d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=38d0d425-ba52-4c0a-a03e-2a65c8e82e2d;Ip=[204.77.163.244];Helo=[edgetransport.garmin.com] X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR04MB4793 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Al, The reference to the POSIX change was included more for a reference to that= discussion, not to say "POSIX did this and so Linux must do it to". In any= case, the documentation presented to the Austin Group was focused more aro= und the issue we ran into and some alternative solutions. In reviewing the = notes from the meeting I didn't get the impression that they added this to = POSIX simply because Solaris and *BSD already had it (reference https://aus= tingroupbugs.net/view.php?id=3D1317, the first solution we suggested). > It penalizes every call of fork() in the system Is the performance hit really that drastic? fork() does a lot of stuff and = this really seems like a drop in the bucket... > adds an extra dirtied cacheline on each socket()/open()/etc. It sounds like we can work to improve that, though. > already has a portable solution What is the solution? Thanks, Nate -----Original Message----- From: Al Viro On Behalf Of Al Viro Sent: Friday, May 15, 2020 11:04 To: Karstens, Nate Cc: Jeff Layton ; J. Bruce Fields ; Arnd Bergmann ; Richard Henderson ; Ivan= Kokshaysky ; Matt Turner ; J= ames E.J. Bottomley ; Helge Deller <= deller@gmx.de>; David S. Miller ; Jakub Kicinski ; Eric Dumazet ; David Laight ; linux-fsdevel@vger.kernel.org; linux-arch@vger.kernel.org; l= inux-alpha@vger.kernel.org; linux-parisc@vger.kernel.org; sparclinux@vger.k= ernel.org; netdev@vger.kernel.org; linux-kernel@vger.kernel.org; Changli Ga= o Subject: Re: [PATCH v2] Implement close-on-fork CAUTION - EXTERNAL EMAIL: Do not click any links or open any attachments un= less you trust the sender and know the content is safe. On Fri, May 15, 2020 at 10:23:17AM -0500, Nate Karstens wrote: > This functionality was approved by the Austin Common Standards > Revision Group for inclusion in the next revision of the POSIX > standard (see issue 1318 in the Austin Group Defect Tracker). It penalizes every call of fork() in the system (as well as adds an extra d= irtied cacheline on each socket()/open()/etc.), adds memory footprint and c= omplicates the API. All of that - to deal with rather uncommon problem tha= t already has a portable solution. As for the Austin Group, the only authority it has ever had derives from co= nsensus between existing Unices. "Solaris does it, Linux and *BSD do not" = translates into "Austin Group is welcome to take a hike". BTW, contrary to the lovely bit of misrepresentation in that thread of thei= rs (" suggests that" !=3D "someone's comment under LWN article say= s it _appears_ that"), none of *BSD do it. IMO it's a bad idea. NAKed-by: Al Viro ________________________________ CONFIDENTIALITY NOTICE: This email and any attachments are for the sole use= of the intended recipient(s) and contain information that may be Garmin co= nfidential and/or Garmin legally privileged. If you have received this emai= l in error, please notify the sender by reply email and delete the message.= Any disclosure, copying, distribution or use of this communication (includ= ing attachments) by someone other than the intended recipient is prohibited= . Thank you.