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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.googlemail.com with ESMTPSA id f4-20020a7bc8c4000000b0038ebbe10c5esm12942575wml.25.2022.04.25.23.36.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 Apr 2022 23:36:53 -0700 (PDT) Message-ID: <18ffeaf2-cb4c-ad6f-51eb-a4cdd5cd3c31@redhat.com> Date: Tue, 26 Apr 2022 08:36:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 To: Mathieu Desnoyers , Steven Rostedt References: <1218866473.10909.1649432186473.JavaMail.zimbra@efficios.com> <3c11308e-006a-a7e9-8482-c6b341690530@redhat.com> <1622857974.11247.1649441213797.JavaMail.zimbra@efficios.com> <20220425100434.2f5d18bb@gandalf.local.home> <892959086.34940.1650902572304.JavaMail.zimbra@efficios.com> In-Reply-To: <892959086.34940.1650902572304.JavaMail.zimbra@efficios.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Subject: Re: [lttng-dev] Unexport of kvm_x86_ops vs tracer modules X-BeenThere: lttng-dev@lists.lttng.org X-Mailman-Version: 2.1.39 Precedence: list List-Id: LTTng development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Paolo Bonzini via lttng-dev Reply-To: Paolo Bonzini Cc: Sean Christopherson , lttng-dev , KVM list Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" On 4/25/22 18:02, Mathieu Desnoyers wrote: >> Now another solution is to make the fast assigns available to anyone, and >> to allow you to simply pass in a pointer and size to have the data written >> into it. That is, you get the results of the TRACE_EVENT and not have to >> depend on internal data from the tracepoint. > If the fast assign can then be used on a field-per-field basis, maybe this > could work, but AFAIK the fast-assign macro is open-coded C, which makes this > not straightforward. > > If it's a all-or-nothing approach where the fast-assign needs to serialize all > fields, this would require that lttng copies the data into a temporary area, > which is something I want to avoid for filtering and event notification per-field > payload capture purposes. It wouldn't be great; but it wouldn't be any worse than doing any complex calculations inside an "if (trace_xyz_enabled())", and passing them as arguments to the tracepoint function, which is what you suggested earlier. Paolo _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev