Hi, On Thu, Mar 19, 2020 at 3:30 PM Yuanqi Li <[email protected]> wrote: > Recently we've been looking for new directions. One of the ideas is to merge > JVM and kernel together, so that kernel can expose more system information > (e.g., memory usage and layout, scheduling, network stack) to JVM. Some > potential benefits may include better Java application performance, better GC > performance, faster bootstrapping time, etc. The main target will be > serverless functions (e.g., AWS Lambda) where most tasks are short lived > function invocations. A slow start of JVM is prohibitive. An insight is that > both the guest OS and JVM are virtual machines essentially, a lot of language > and security checks in JVM may be redundant given that the guest OS is > already well isolated. Memory allocation and reclaim may also work better > since OS can see semantic information of memory pages. So our first try will > be making JVM and kernel share the same memory management subsystem.
Yeah, I think this is an interesting direction! Merging the JVM and the OS was one of the things we were looking to do with OSv, as you can see from the JVM memory balloon feature. > For the new project, I am doing preliminary experiments to collect > performance numbers and estimate potential benefits of the design. OSv is a > very interesting and promising kernel that we'd like to dig more. Its boot > time is blazing fast with Firecracker. I also saw from the original ATC paper > and source code that it has a JVM ballooning mechanism. But I didn't see how > it could work with unmodified JVM. In addition, if I want to compile both OSv > and OpenJDK together from source into a single bootable image, is there any > solutions or resources? I didn't see such documentation in OSv's github wiki. I don't remember if we ever built JVM from sources (I'm CC'ing Calle for this), but it shouldn't be too hard to do. The way it works in OSv is that you pass the "image" option to "./scripts/build" to build an image with OSv and some applications: https://github.com/cloudius-systems/osv#building-osv-kernel-and-creating-images What you need to do is define a OSv "module" or "application" that builds JVM from sources. You can find an example of Python being built from sources here: https://github.com/cloudius-systems/osv-apps/tree/master/python27-fromsource Please note that OSv still consumes the applications as ELF executables and shared libraries, and not combine them into one binary like other unikernels like Mirage do. > I know that OSv is designed to support arbitrary unmodifed Linux binaries. So > our idea diverges from OSv's goal. But given the popularity of FaaS and > microservices, a dedicated bootable JVM worths a try. Or we may later find > some low-intrusive disign that doesn't conflict with OSv's goal. We wanted to run Linux executables out-of-the-box, but did not rule out OSv-specific APIs. If you allow yourself to modify the JVM sources, then there's really no problem in adding more OSv "system calls" (they're really functions) to do what you need to do. Hope this helps! - Pekka -- You received this message because you are subscribed to the Google Groups "OSv Development" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/osv-dev/CAGUyND--eYUdV2smCcmD-bHbu7_9ngfdSbSkG7QH5MVymdQOOg%40mail.gmail.com.
