lkml.org 
[lkml]   [2006]   [Oct]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] Thaw userspace and kernel space separately.
From
Date
Hi.

On Mon, 2006-10-23 at 12:26 +0200, Rafael J. Wysocki wrote:
> On Monday, 23 October 2006 01:48, Nigel Cunningham wrote:
> > Modify process thawing so that we can thaw kernel space without thawing
> > userspace, and thaw kernelspace first. This will be useful in later
> > patches, where I intend to get swsusp thawing kernel threads only before
> > seeking to free memory.
>
> Please explain why you think it will be necessary/useful.
>
> I remember a discussion about it some time ago that didn't indicate
> we would need/want to do this.

This is needed to make suspending faster and more reliable when the
system is in a low memory situation. Imagine that you have a number of
processes trying to allocate memory at the time you're trying to
suspend. They want so much memory that when you come to prepare the
image, you find that you need to free pages. But your swapfile is on
ext3, and you've just frozen all processes, so any attempt to free
memory could result in a deadlock while the vm tries to swap out pages
using the frozen kjournald. So you need to thaw processes to free the
memory. But thawing processes will start the processes allocating memory
again, so you'll be fighting an uphill battle.

If you can only thaw the kernel threads, you can free memory without
restarting userspace or deadlocking against a frozen kjournald.

Regards,

Nigel


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

\
 
 \ /
  Last update: 2006-10-23 14:13    [W:0.068 / U:1.664 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site