From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 234DBC433FE for ; Wed, 6 Oct 2021 15:02:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0889261166 for ; Wed, 6 Oct 2021 15:02:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239100AbhJFPEB (ORCPT ); Wed, 6 Oct 2021 11:04:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238996AbhJFPEA (ORCPT ); Wed, 6 Oct 2021 11:04:00 -0400 Received: from mail-yb1-xb36.google.com (mail-yb1-xb36.google.com [IPv6:2607:f8b0:4864:20::b36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EB74C061755 for ; Wed, 6 Oct 2021 08:02:08 -0700 (PDT) Received: by mail-yb1-xb36.google.com with SMTP id w10so6121748ybt.4 for ; Wed, 06 Oct 2021 08:02:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=MzEyLfp/eaHfYFCvoWfOxrcj4KYXSDgQLbhw8YX+9RQ=; b=ta783nvpkwKOOuucrK44IRRZ9hsio5xXDjvuB9yPa0HD0qE19p3Q4KAilwYpao2Q1n /nNINPBvLQE6n0Mjih3w+sAS+eNMP0JqJynoUtkoX3L8FnPZ6D909MtUhWc0x1lqIwKr I75rTIamcY3eF7Zn2h7FYdOKahWN6t0lE2WxcbNT3KPeSXoG9FnXjf4zkYEVH8bdehPD AES4Z8OtqtuO0iGM7ej/L8A3TQn3beFpQ+dLiQlBnMalAJDGX0ac669Mqpjv94Xxb8oX ldmGzRMon9eDT7CoGa6HBE1/ZEcLnn8xoWaZW6Jx3Ln4YtFCGcJ4lJfPw8yndXkoqCt5 UGng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=MzEyLfp/eaHfYFCvoWfOxrcj4KYXSDgQLbhw8YX+9RQ=; b=RWm+MSjkcv244XHo6fXKHT6+MhKs1A+xP3e6O51YPWX9ARWvYL3Se3OZuSjRBCf1Qt qNwM/kDz3cmFk/wlo5OzvdERzEUAxKZTyS+nGSro0GsZjuQy8ba6u2cvJSYajfC+Eq1p idefZWxK4xqtRbW1rkiNBR8hQt9/OWPJX8zd7QV+SAhrf0RvN01aaaMWOYs8jePei6/B SDt5mWaLgwxvSod5n8OidAaJ9ZSMJcAxzP/D3MJvqKjGe9ES+SHSZjm+0ZkC4hWl7IbD zVnGq1WapaFQdTpSl6sI1Cq5jZsQ7ar2MlX4u+5q747PxrM7xKdQPGZRNnVNqJmsr+Uj jxmw== X-Gm-Message-State: AOAM533XBT4zThUbouzBjvxLVGvUPFVyENJI5r5uRHKPhq5pIFipUXUr UAi+LIhIg1Xf6y62/ROAUKRWPU136X3biKSbMBLHrQ== X-Google-Smtp-Source: ABdhPJzHHjr+U17m6GiWu/VvrpzHwzmwnyEEuH0irvtCoZwtYfAaRRTS4+nFij482usItX590WL/sqUymh0V1yrnZeU= X-Received: by 2002:a25:3:: with SMTP id 3mr29737607yba.418.1633532527401; Wed, 06 Oct 2021 08:02:07 -0700 (PDT) MIME-Version: 1.0 References: <20211001205657.815551-1-surenb@google.com> <20211001205657.815551-3-surenb@google.com> <20211005184211.GA19804@duo.ucw.cz> <20211005200411.GB19804@duo.ucw.cz> <6b15c682-72eb-724d-bc43-36ae6b79b91a@redhat.com> In-Reply-To: <6b15c682-72eb-724d-bc43-36ae6b79b91a@redhat.com> From: Suren Baghdasaryan Date: Wed, 6 Oct 2021 08:01:56 -0700 Message-ID: Subject: Re: [PATCH v10 3/3] mm: add anonymous vma name refcounting To: David Hildenbrand Cc: Michal Hocko , John Hubbard , Pavel Machek , Andrew Morton , Colin Cross , Sumit Semwal , Dave Hansen , Kees Cook , Matthew Wilcox , "Kirill A . Shutemov" , Vlastimil Babka , Johannes Weiner , Jonathan Corbet , Al Viro , Randy Dunlap , Kalesh Singh , Peter Xu , rppt@kernel.org, Peter Zijlstra , Catalin Marinas , vincenzo.frascino@arm.com, =?UTF-8?B?Q2hpbndlbiBDaGFuZyAo5by16Yym5paHKQ==?= , Axel Rasmussen , Andrea Arcangeli , Jann Horn , apopple@nvidia.com, Yu Zhao , Will Deacon , fenghua.yu@intel.com, thunder.leizhen@huawei.com, Hugh Dickins , feng.tang@intel.com, Jason Gunthorpe , Roman Gushchin , Thomas Gleixner , krisman@collabora.com, chris.hyser@oracle.com, Peter Collingbourne , "Eric W. Biederman" , Jens Axboe , legion@kernel.org, Rolf Eike Beer , Cyrill Gorcunov , Muchun Song , Viresh Kumar , Thomas Cedeno , sashal@kernel.org, cxfcosmos@gmail.com, Rasmus Villemoes , LKML , linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm , kernel-team Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Oct 6, 2021 at 2:27 AM David Hildenbrand wrote: > > On 06.10.21 10:27, Michal Hocko wrote: > > On Tue 05-10-21 23:57:36, John Hubbard wrote: > > [...] > >> 1) Yes, just leave the strings in the kernel, that's simple and > >> it works, and the alternatives don't really help your case nearly > >> enough. > > > > I do not have a strong opinion. Strings are easier to use but they > > are more involved and the necessity of kref approach just underlines > > that. There are going to be new allocations and that always can lead > > to surprising side effects. These are small (80B at maximum) so the > > overall footpring shouldn't all that large by default but it can grow > > quite large with a very high max_map_count. There are workloads which > > really require the default to be set high (e.g. heavy mremap users). So > > if anything all those should be __GFP_ACCOUNT and memcg accounted. > > > > I do agree that numbers are just much more simpler from accounting, > > performance and implementation POV. > > +1 > > I can understand that having a string can be quite beneficial e.g., when > dumping mmaps. If only user space knows the id <-> string mapping, that > can be quite tricky. > > However, I also do wonder if there would be a way to standardize/reserve > ids, such that a given id always corresponds to a specific user. If we > use an uint64_t for an id, there would be plenty room to reserve ids ... > > I'd really prefer if we can avoid using strings and instead using ids. I wish it was that simple and for some names like [anon:.bss] or [anon:dalvik-zygote space] reserving a unique id would work, however some names like [anon:dalvik-/system/framework/boot-core-icu4j.art] are generated dynamically at runtime and include package name. Packages are constantly evolving, new ones are developed, names can change, etc. So assigning a unique id for these names is not really feasible. That leaves us with the central facility option, which as I described in my previous email would be prohibitive from performance POV (IPC every time we have a new name or want to convert id to name). I'm all for simplicity but the simple approach of using ids instead of names unfortunately would not work for our usecases. > > -- > Thanks, > > David / dhildenb >