Linked by Kroc Camen on Thu 25th Dec 2008 07:50 UTC, submitted by diegocg
Linux Heise Open Source provides an extensive breakdown of the innovations present in the latest release of the Linux kernel, announced by Linus Torvalds. This version adds the first version of Ext4 as a stable filesystem, the much-anticipated GPU memory manager which will be the foundation of a renewed graphic stack, support for Ultra Wide Band (Wireless USB, UWB-IP), memory management scalability and performance improvements, a boot tracer, disk shock protection, the phonet network protocol, support of SSD discard requests, transparent proxy support, high-resolution poll()/select()... full Changelog here
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RE[9]: the list is impressive
by abraxas on Mon 29th Dec 2008 23:29 UTC in reply to "RE[8]: the list is impressive"
abraxas
Member since:
2005-07-07

According to me there are only two categories Monolithic or Microkernel. This whole hybrid kernel thing is just marketing.


Oh ok, according to YOU! Case closed! Too bad you are completely wrong. Have you heard of XNU which is a hybrid kernel or XOK, MIT's exokernel which is smaller than a microkernel but does not use message passing?

udev does nothing to make linux more microkernel like. It is a dev filesystem that manages the /dev directories and symlinks. Udev just listens for kernel events and manages /dev entries.


Methinks you don't understand the point behind microkernels. The main reason is to move things out of kernelspace to avoid errors that can take down the entire system. By moving more things out of the Linux kernel into userspace it allows some of the same advantages.

Fuse has a kernel module that runs in privileged or supervisor mode.


This is true but the filesystem implementations are completely in userspace.

In a microkernel nothing the kernel in privileged mode only handles IPC, address space management, interrupts and thread scheduling. Everything else is in non-privileged mode.


I guess most implementation of Mach are not microkernels then since they use co-location to move servers into kernelspace because of the atrocious performance of pure microkernels.

Reply Parent Score: 2

akrosdbay Member since:
2008-06-09



Oh ok, according to YOU! Case closed! Too bad you are completely wrong. Have you heard of XNU which is a hybrid kernel or XOK, MIT's exokernel which is smaller than a microkernel but does not use message passing?


You clearly have no clue. We were talking about microkernels and monolithic kernels. Hybrid kernels are supposed to be an amalgam of those two concepts. The MIT exokernel is neither of those.

I didn't say they are the only two ways of doing things.


Methinks you don't understand the point behind microkernels. The main reason is to move things out of kernelspace to avoid errors that can take down the entire system. By moving more things out of the Linux kernel into userspace it allows some of the same advantages.


Wrong! udev has nothing to do with device drivers or privileged code. First understand what udev does before you talk out of your nether regions.

I was pointing out that your examples are completely wrong. You are trying to convey a point but you don't even understand the examples you are using.


This is true but the filesystem implementations are completely in userspace.


Therefore FUSE is a bad example because all of it is not in user space. It is a good abstraction but it doesn't make the OS, FUSE is running on any more of a microkernel. The reason being a kernel mode driver is need to make it work.


I guess most implementation of Mach are not microkernels then since they use co-location to move servers into kernelspace because of the atrocious performance of pure microkernels.


Most commercial implementations of Mach like Mac OS X darwin are no longer microkernels.

One word, QNX. You really need to pay attention. QNX beats the pants off linux in scaling down, RT and latency. Got any more ignorance to spread?

Edited 2008-12-30 09:56 UTC

Reply Parent Score: 1

RE[11]: the list is impressive
by abraxas on Tue 30th Dec 2008 16:10 in reply to "RE[10]: the list is impressive"
abraxas Member since:
2005-07-07

You clearly have no clue. We were talking about microkernels and monolithic kernels. Hybrid kernels are supposed to be an amalgam of those two concepts. The MIT exokernel is neither of those.

I didn't say they are the only two ways of doing things.


Actually you did. "According to me there are only two categories Monolithic or Microkernel."


Wrong! udev has nothing to do with device drivers or privileged code. First understand what udev does before you talk out of your nether regions.

I was pointing out that your examples are completely wrong. You are trying to convey a point but you don't even understand the examples you are using.


What are you talking about? Where did I mention device drivers in connection with udev? Maybe you haven't been around that long to remember devfs. Devfs was the precursor to udev and it was inside the kernel. The point I was trying to make is that when feasible Linux has moved things out of the kernel.

Therefore FUSE is a bad example because all of it is not in user space. It is a good abstraction but it doesn't make the OS, FUSE is running on any more of a microkernel. The reason being a kernel mode driver is need to make it work.


I never said Linux was a microkernel or was trying to be a microkernel. I just said that concepts from microkernels have entered into other kernels like Linux. The main concept behind microkernels is running as little code in kernelspace as possible. Linux is pushing code out to userspace when it is feasible. Microkernels have done it the other way around and starting pulling things into kernelspace when performance suffers dramatically in userspace.

One word, QNX. You really need to pay attention. QNX beats the pants off linux in scaling down, RT and latency. Got any more ignorance to spread?


It depends on architecture. Context switching on x86 is expensive. QNX and other microkernels don't perform well on x86.

Reply Parent Score: 2