On 12Mar2009 22:09, Martin v. L?wis <mar...@v.loewis.de> wrote: | > Let me try some examples. | > Suppose I'm running my applications on a laptop and I don't want the | > disk to be spinning continually while I work. I'm willing to take the | > risk of data loss in order to extend my battery life. | | So when you select "Save" in your application, would you like the data | to be saved, or would you accept that they get lost?
Often, I will accept that they get lost. Why? Because that will only happen with and OS/hardware failure, and I expect those to be close to never. | If the latter, | what kind of interaction would you perform with your application to | indicate that you *do* want the data to appear on disk? I don't. I type "sync" to a convenient shell prompt. On a UNIX OS, that will not return until all outstanding data at the time of issuing the command have been commited to disc. As you can see, that places the timing in the hands of the user. Where it belongs, not impacting the performance of the system except at my own command. I speak as one who keeps his bogofilter spam datbase on a RAM disc because bogofilter, too, is subject to atrocious sync overuse, since it uses a database library that overuses sync. Testing shows at least one and possibly more _orders_of_magnitude_ improvement in behaviour. Every so often I copy the bogofilter db back to real disc. The wholse point of a good OS on decent hardware is that one can commit data to the _OS_, and trust that it will reach the disc in due course. Fsync shows an app that doesn't trust the OS. I hope you don't believe that handing the data to the disc drive guarentees it has made it to the magnetic medium. It should do, but the drive will probably acknowledge the data before the medium has completed updating. Cheers, -- Cameron Simpson <c...@zip.com.au> DoD#743 http://www.cskk.ezoshosting.com/cs/ Isaac Asimov once remarked that friends had chided him for not patenting the electronic pocket calculator, since he wrote of similar devices back in the 1940's. His reply, "Have you ever noticed I only described what it looked like on the *outside*?" - i...@mediaone.net _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
