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([2001:b07:6468:f312:3c1c:ffba:c624:29b8]) by smtp.gmail.com with ESMTPSA id l1sm3053400ejd.114.2020.05.27.08.00.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 27 May 2020 08:00:45 -0700 (PDT) Subject: Re: [PATCH v3 0/7] Statsfs: a new ram-based file system for Linux kernel statistics To: Andrew Lunn , Emanuele Giuseppe Esposito Cc: Jakub Kicinski , kvm@vger.kernel.org, Christian Borntraeger , Jim Mattson , Alexander Viro , Emanuele Giuseppe Esposito , David Rientjes , Jonathan Adams , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org References: <20200526110318.69006-1-eesposit@redhat.com> <20200526153128.448bfb43@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net> <6a754b40-b148-867d-071d-8f31c5c0d172@redhat.com> <20200527133309.GC793752@lunn.ch> From: Paolo Bonzini Message-ID: Date: Wed, 27 May 2020 17:00:41 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200527133309.GC793752@lunn.ch> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 27/05/20 15:33, Andrew Lunn wrote: >> I don't really know a lot about the networking subsystem, and as it was >> pointed out in another email on patch 7 by Andrew, networking needs to >> atomically gather and display statistics in order to make them consistent, >> and currently this is not supported by stats_fs but could be added in >> future. > > Do you have any idea how you will support atomic access? It does not > seem easy to implement in a filesystem based model. Hi Andrew, there are plans to support binary access. Emanuele and I don't really have a plan for how to implement it, but there are developers from Google that have ideas (because Google has a similar "metricfs" thing in-house). I think atomic access would use some kind of "source_ops" struct containing create_snapshot and release_snapshot function pointers. Paolo