Re: Back to the future.

From: David Lang
Date: Fri Apr 27 2007 - 21:30:10 EST

On Fri, 27 Apr 2007, Linus Torvalds wrote:

On Sat, 28 Apr 2007, Rafael J. Wysocki wrote:

It's doubly bad, because that idiocy has also infected s2ram. Again,
another thing that really makes no sense at all - and we do it not just
for snapshotting, but for s2ram too. Can you tell me *why*?

Why we freeze tasks at all or why we freeze kernel threads?

In many ways, "at all".

I _do_ realize the IO request queue issues, and that we cannot actually do
s2ram with some devices in the middle of a DMA. So we want to be able to
avoid *that*, there's no question about that. And I suspect that stopping
user threads and then waiting for a sync is practically one of the easier
ways to do so.

So in practice, the "at all" may become a "why freeze kernel threads?" and
freezing user threads I don't find really objectionable.

there was a thread last week (or so) about splitting up the process list, one list for normal user processes, one for kernel threads, and one for dead processes waiting to be reaped.

it almost sounds like what you want to do is to act as if the normal user threads weren't there for a short time (while you make the snapshot) and then recover them to continue and save the snapshot.

David Lang
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at