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Wed, 11 Sep 2024 16:11:51 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id n2DeMkfB4WYnfAAAD6G6ig (envelope-from ); Wed, 11 Sep 2024 16:11:51 +0000 From: Fabiano Rosas To: Peter Xu Cc: qemu-devel@nongnu.org, Prasad Pandit , Yichen Wang , Bryan Zhang , Hao Xiang , Yuan Liu Subject: Re: [PATCH] migration/multifd: Fix build for qatzip In-Reply-To: References: <20240910210450.3835123-1-peterx@redhat.com> <87v7z3qjih.fsf@suse.de> <87jzfjqgwc.fsf@suse.de> Date: Wed, 11 Sep 2024 13:11:48 -0300 Message-ID: <87h6amqiez.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MISSING_XM_UA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_SEVEN(0.00)[7]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo] Received-SPF: pass client-ip=195.135.223.130; envelope-from=farosas@suse.de; helo=smtp-out1.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Peter Xu writes: > On Tue, Sep 10, 2024 at 07:32:19PM -0300, Fabiano Rosas wrote: >> I'm trying to find a way of having more code compiled by default and >> only a minimal amount of code put under the CONFIG_FOO options. So if >> some multifd code depends on a library call, say deflateInit, we make >> that a multifd_deflate_init and add a stub for when !ZLIB (just an >> example). I'm not sure it's feasible though, I'm just bouncing the idea >> off of you. > > Not sure how much it helps. It adds more work, add slightly more code to > maintain (then we will then need to maintain the shim layer, and that's > per-compressor), while I am not sure it'll be good enough either.. For > example, even if it compiles it can still run into constant failure when > with the real library / hardware underneath. > > This not so bad to me yet: do you still remember or aware of the "joke" on > how people remove a feature in Linux? One can introduce a bug that can > directly crash when some feature enabled, then after two years the > developer can say "see, this feature is not used by anyone, let's remove > it". > > I think it's a joke (which might come from reality..) but it's kind of a > way that how we should treat these compressors as a start, IMHO. AFAIU > many of these compressors start with PoC-type projects where it's used to > justify the hardware features. The next step is in production use but that > requires software vendors to involve, IIUC. I think that's what we're > waiting for, on company use it in more serious way that sign these features > off. > > I don't think all such compressors will reach that point. Meanwhile I > don't think we (as qemu migration maintainers) can maintain that code well, > if we don't get sponsored by people with hardwares to test. > > I think it means it's not our job to maintain it at 100%, yet so far. We > will still try our best, but that's always limited. As we discussed > before, we always need to rely on vendors so far for most of them. > > If after a few releases we found it's broken so bad, it may mean it > finished its job as PoC or whatever purpose it services. It means we could > choose to move on, with no joking. > > That's why I think it's not so urgent, and maybe we don't need extra effort > to make it harder for us to notice nobody is using it - we keep everything > we know productions are actively using seriously (like multifd, postcopy, > etc.). Either some compressors become part of the serious use case, or we > move on. I recently do find more that the only way to make QEMU keep > living well is to sometimes throw things away.. Ok, that's all fair. I agree we can continue with that policy. Thanks for sharing your thoughts.