Re: Stack consumption in NPTL

llothar <llothar@xxxxxx> writes:
On 7 Mrz., 16:39, Chetan <chetan...@xxxxxxxxx> wrote:

Is this the case? Is it documented anywhere?

I asked this many times. Nobody can answer it. It is AFAIK only
specified on MacOSX where then MachTask has a 16KB kernel stack. I
wasn't even getting an answer on this list if there is a different
kernel stack and what default size it is.

'kernel stack' and 'userspace stack' are two completely unrelated
things: Because every 'usual' (NPTL, LinuxThreads) thread on
Linux-based systems is associated with a 'kernel schedulable entity'
('task', 1:1 threading), every thread has a kernel stack associated
with it, to be used while the thread is executing in the kernel. As
opposed to the userspace stack, whose pages, up to configured maximum
size, are allocated on demand, the kernel stack consumes a certain
amount of physical memory during the lifetime of the thread it belongs
to. How much depends on the kernel configuration: The defaults is 8K per
thread, with 4K per thread being selectable when configuring a kernel
source tree for compilation (for some weird reason, this is part of
'Kernel hacking/ Kernel debugging').
.

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