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([2001:b07:6468:f312:7848:99b4:482a:e888]) by smtp.gmail.com with ESMTPSA id z6sm21652291wrp.95.2020.03.23.03.12.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 23 Mar 2020 03:12:17 -0700 (PDT) Subject: Re: [PATCH 0/7] tools/kvm_stat: add logfile support To: Stefan Raspl , kvm@vger.kernel.org Cc: rkrcmar@redhat.com References: <20200306114250.57585-1-raspl@linux.ibm.com> <7f396df1-9589-6dd0-0adf-af4376aa8314@redhat.com> From: Paolo Bonzini Message-ID: <5c350f55-64be-43fc-237d-7f71b4e9afdc@redhat.com> Date: Mon, 23 Mar 2020 11:12:19 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 23/03/20 10:58, Stefan Raspl wrote: > Thx! > As for SIGHUP: The problem that I see with logrotate and likewise approaches is > how the heading is being handled: If it is reprinted every x lines (like the > original logging format in kvmstat does), then it messes up any chance of > loading the output in external tools for further processing. > If the heading is printed once only, then it will get pushed out of the log > files at some time - which is fatal, since '-f ' allows to specify > custom fields, so one cannot reconstruct what the fields were. For CSV output, can't you print the heading immediately after SIGHUP reopens the files? (Maybe I am missing something and this is a stupid suggestion, I don't know). Paolo > That's why I did things as I did - which works great for .csv output. > I'd really like to preserve the use-case where a user has a chance to > post-process the output, especially .csv, in other tools. So how how about we do > both, add support for SIGHUP for users who want to use logrotate (I imagine this > would be used with the original logging format only), and keep the suggested > support for 'native' log-rotation for .csv users?