switching from kernel mode to user mode?

• Next message: Jan Kara: "Bug in fs/block_dev.c in 2.2.14 and 2.3.42"
• Previous message: Paul: "Re: 2.2.14 kernel -- problems with NFS (and tcp?)"
• Next in thread: Ralf Baechle: "Re: switching from kernel mode to user mode?"
• Reply: Ralf Baechle: "Re: switching from kernel mode to user mode?"
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

I am doing some measurement to see how long Linux runs in
the kernel mode. I need to capture all the places where
Linux actually switches from kernel mode to user mode.

I am looking at ver 2.2.12 on i386. Currently I set a checkpoint
right before RESTORE_ALL in arch/i386/kernel/entry.S (excluding
the excution paths coming from ret_from_intr).

Apparently, the results I got seem to suggest I am missing other
places where kernel can switch back to user mode. One of
such a place that I am suspicious of is __switch_to() called inside
schedule(). So the question is :

Can __switch_to() actually go back directly to user mode?
Are there any other places where kernel jumps back to user mode?

Thanks.

Jun

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

• Next message: Jan Kara: "Bug in fs/block_dev.c in 2.2.14 and 2.3.42"
• Previous message: Paul: "Re: 2.2.14 kernel -- problems with NFS (and tcp?)"
• Next in thread: Ralf Baechle: "Re: switching from kernel mode to user mode?"
• Reply: Ralf Baechle: "Re: switching from kernel mode to user mode?"
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

This archive was generated by hypermail 2b29 : Tue Feb 15 2000 - 21:00:16 EST