From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) Subject: Re: [PATCH RFC] mnt: umount mounts one by one in umount_tree() Date: Wed, 14 Jun 2017 04:37:19 -0500 Message-ID: <87wp8ec3lc.fsf@xmission.com> References: <20170512070838.5037-1-avagin@openvz.org> <1497405190.2595.3.camel@themaw.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <1497405190.2595.3.camel-PKsaG3nR2I+sTnJN9+BGXg@public.gmane.org> (Ian Kent's message of "Wed, 14 Jun 2017 09:53:10 +0800") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Ian Kent Cc: linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Linux Containers , Andrei Vagin , Alexander Viro List-Id: containers.vger.kernel.org SWFuIEtlbnQgPHJhdmVuQHRoZW1hdy5uZXQ+IHdyaXRlczoKCj4gT24gRnJpLCAyMDE3LTA1LTEy IGF0IDAwOjA4IC0wNzAwLCBBbmRyZWkgVmFnaW4gd3JvdGU6Cj4+IFdpdGggdGhpcyBwYXRjaCwg d2UgZG9uJ3QgdHJ5IHRvIHVtb3VudCBhbGwgbW91bnRzIG9mIGEgdHJlZSB0b2dldGhlci4KPj4g SW5zdGVhZCBvZiB0aGlzIHdlIHVtb3VudCB0aGVtIG9uZSBieSBvbmUuIEluIHRoaXMgY2FzZSwg d2Ugc2VlIGEgc2lnbmlmaWNhbnQKPj4gaW1wcm92ZW1lbnQgaW4gcGVyZm9ybWFuY2UgZm9yIHRo ZSB3b3Jz0LUgY2FzZS4KPgo+IEluZGVlZCwgdW1vdW50IGhhcyBiZWVuIHZlcnkgc2xvdyBmb3Ig YSB3aGlsZSBub3cuCj4gRXZlbiBhIG1vZGVyYXRlbHkgbGFyZ2UgbnVtYmVyIG9mIG1vdW50cyAo fjEwMDAwKSBiZWNvbWUgcGFpbmZ1bGx5IHNsb3cuCj4KPiBSZSB5b3Ugc3RpbGwgcGVydXNpbmcg dGhpcz8KPiBBbnl0aGluZyBJIGNhbiBkbyB0byBoZWxwPwo+Cj4gRXJpYywgd2hhdCBhcmUgeW91 ciB0aG91Z2h0cyBvbiB0aGlzIGxhdGVzdCBhdHRlbXB0PwoKSSBoYXZlIHNvbWV0aGluZyBzbGln aHRseSBtb3JlIHJlY2VudC4gIFBsZWFzZSBjaGVja291dCBteSBmb3ItbmV4dApicmFuY2ggb2Yg bXkgdXNlcm5zIHRyZWU6CgpnaXQ6Ly9naXQua2VybmVsLm9yZy9wdWIvc2NtL2xpbnV4L2tlcm5l bC9naXQvZWJpZWRlcm0vdXNlci1uYW1lc3BhY2UuZ2l0IGZvci1uZXh0CgpUaGVyZSBpcyBvbmUg b3BlbiBhcmVhIG9mIHNlbWFudGljcyB0aGF0IEkgbG9va2luZyBhdCB3aXRoIFJhbSBQYWkgaW4K dGhlIGhvcGVzIHdlIGNhbiBkcml2ZSBjb25zZW5zdXMgYmVmb3JlIHdlIHRha2UgYW55IHBhdGNo ZXMgZm9yCmJldHRlciBjaGVja3BvaW50LXJlc3RhcnQgc3VwcG9ydC4KCkVyaWMKCl9fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCkNvbnRhaW5lcnMgbWFpbGlu ZyBsaXN0CkNvbnRhaW5lcnNAbGlzdHMubGludXgtZm91bmRhdGlvbi5vcmcKaHR0cHM6Ly9saXN0 cy5saW51eGZvdW5kYXRpb24ub3JnL21haWxtYW4vbGlzdGluZm8vY29udGFpbmVycw== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out01.mta.xmission.com ([166.70.13.231]:37004 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751889AbdFNJoU (ORCPT ); Wed, 14 Jun 2017 05:44:20 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Ian Kent Cc: Andrei Vagin , Alexander Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Linux Containers References: <20170512070838.5037-1-avagin@openvz.org> <1497405190.2595.3.camel@themaw.net> Date: Wed, 14 Jun 2017 04:37:19 -0500 In-Reply-To: <1497405190.2595.3.camel@themaw.net> (Ian Kent's message of "Wed, 14 Jun 2017 09:53:10 +0800") Message-ID: <87wp8ec3lc.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Subject: Re: [PATCH RFC] mnt: umount mounts one by one in umount_tree() Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Ian Kent writes: > On Fri, 2017-05-12 at 00:08 -0700, Andrei Vagin wrote: >> With this patch, we don't try to umount all mounts of a tree together. >> Instead of this we umount them one by one. In this case, we see a significant >> improvement in performance for the worsе case. > > Indeed, umount has been very slow for a while now. > Even a moderately large number of mounts (~10000) become painfully slow. > > Re you still perusing this? > Anything I can do to help? > > Eric, what are your thoughts on this latest attempt? I have something slightly more recent. Please checkout my for-next branch of my userns tree: git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git for-next There is one open area of semantics that I looking at with Ram Pai in the hopes we can drive consensus before we take any patches for better checkpoint-restart support. Eric