Re: Active_mm

[John Levon <levon@movementarian.org>]

On Fri, Oct 04, 2002 at 01:08:01PM +0200, R!SC wrote:

> what is active_mm field in task_struct?
> it's often used in  schedule alghoritm.

active_mm contains the active user-space virtual memory mappings. For
"normal" tasks, mm == active_mm. For kernel tasks, though, they don't
care about user-space mappings, so instead of fully flushing page tables
etc., active_mm is set to the previous task's (the one being scheduled
out) mm (see context_switch), and the mm's mm_count is incremented in
case the other "real" users of the mm (mm_users) die.

task->mm is NULL for kernel threads.

This is very rough, and doesn't seem quite right. I don't know quite
what effect TLBSTATE_LAZY actually has on i386 (it only seems to affect
SMP which I don't follow ...)

With any luck, somebody who has a clue about this can comment

regards
john

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