On 07/29/2015 09:28 AM, Jamie Strandboge wrote: > On 07/29/2015 11:09 AM, Tyler Hicks wrote: >> On 2015-07-29 11:25:27, Alberto Mardegan wrote: >>> On 07/29/2015 07:07 AM, Tyler Hicks wrote: > >>>> The exec() will need to occur after special process initialization >>>> such as setting rlimits, configuring cgroups, etc., but before >>>> attempting to preload any libraries. >>>> >>>> I've prototyped the difference with a simple proof-of-concept of a >>>> booster daemon and app program and the exec() slows down things a >>>> considerable amount. Any benchmarks should definitely include such >>>> a change in order to not get any hopes up by looking at the >>>> non-exec()ing benchmark numbers. >>> >>> But the exec() does not necessarily need to load the application, >>> right? It could happen when the user has not yet chosen which >>> application to start, and instead of executing an app, it could exec() >>> into a loader process which does all library preloading and >>> initializing, and then (when the user launches an app) dlopen the app, >>> close any unneeded file descriptors, call aa_change_profile and >>> finally run main(). Then of course it would have to quit, and not be >>> reused. >> >> Yes, exactly! >> >>> This would still preserve the ASLR, wouldn't it? >> >> Yes. I think there will still be plenty of speed benefits. I don't think >> the memory footprint benefits of the booster processes will be nearly as >> good, though. My whole point is that it is worth benchmarking because I >> think we'll still good performance. >> > I think it is important to note (and please correct me if I am wrong! :) that, > today, there is no memory footprint benefit to lose because, today, we have a > full fork/exec of each app. Therefore if we can realize 'plenty of speed > benefits' as Tyler believes we can (and that people should benchmark), that > is a > complete 'win' for the platform. > Not true, there certainly is a small foot print. The booster code will increase an apps process size a small amount, and having a pool of available booster apps will also take some more memory. The loss shouldn't be large but it will be there.
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