Re: voluntary-preempt-2.6.8.1-P9 : big latency when logging on console

[Ingo Molnar <mingo@elte.hu>]

* P.O. Gaillard <pierre-olivier.gaillard@fr.thalesgroup.com> wrote:

> Hello,
> 
> I have a 1.6ms latency every time I log in with P9.

could you try the patch below, ontop of P9? (or ontop of the latest, -Q5
patch)

The problem with font loading is that vt_ioctl runs with the BKL held
(as all ioctls) which disables preemption, but in this case it seems
pretty safe to drop the lock - the vga console has its own spinlock.

	Ingo

--- linux/drivers/video/console/vgacon.c.orig	
+++ linux/drivers/video/console/vgacon.c	
@@ -763,6 +763,7 @@ static int vgacon_do_font_op(struct vgas
 		charmap += 4 * cmapsz;
 #endif
 
+	unlock_kernel();
 	spin_lock_irq(&vga_lock);
 	/* First, the Sequencer */
 	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
@@ -848,6 +849,7 @@ static int vgacon_do_font_op(struct vgas
 		vga_wattr(state->vgabase, VGA_AR_ENABLE_DISPLAY, 0);	
 	}
 	spin_unlock_irq(&vga_lock);
+	lock_kernel();
 	return 0;
 }