From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Petazzoni Date: Tue, 2 Dec 2014 10:30:21 +0100 Subject: [Buildroot] [PATCH 4/4] pkg-download: check hasahes for locally cached files In-Reply-To: <87fvcy2yhi.fsf@dell.be.48ers.dk> References: <20141202093148.1a1f7db7@free-electrons.com> <87fvcy2yhi.fsf@dell.be.48ers.dk> Message-ID: <20141202103021.6e75224a@free-electrons.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Dear Peter Korsgaard, On Tue, 02 Dec 2014 10:27:05 +0100, Peter Korsgaard wrote: > > So in essence, from now on, at each build, we are re-checking the > > hashes, while previously they were checked only when the file was > > downloaded. Not that great for build time, but well, again maybe the > > time to check the hashes is negligible compared to the build time. And > > we can assume that a big tarball, which takes a certain time to hash, > > will also contain a lot of source code to build, so the time to > > calculate the hash is proportional to the build time of the package. So > > if you're ready to spend several minutes to build Qt, you're probably > > ready to wait a few more seconds to calculate the hash of the Qt > > tarball each time. > > I doubt it adds any significant time. Probably the hash and extract > steps are largely I/O bound, so "pre-heating" the page cache by > calculating a hash on the tarball before extracting it shouldn't matter > much. True. Anyway, my comment really wasn't rejecting the idea, just pointing out the additional stuff we are doing. Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com