Re: max Nr of tasks = 4092 for i386

From: Brian Gerst (bgerst@quark.vpplus.com)
Date: Sun Apr 16 2000 - 20:30:43 EST

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Michael Mess wrote:
>
> Hi!
>
> in /usr/src/linux/include/linux/tasks.h I read:

[snip]

> Why is NR_TASKS limited to 4092 for x86 ?

This limitation has been removed in more recent kernels. Older kernels
used hardware task switching on the x86 by using 2 GDT (global
descriptor table) entries per task. There are only 8192 GDT entries
available, and the kernel needs a few for other uses. Newer kernels use
2 GDT entries per cpu and then switch tasks in software, which allows
for an unlimited number of tasks and keeps the GDT size small.

Brian Gerst

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