On 5/22/07, Ingo Molnar <[email protected]> wrote:
* Con Kolivas <[email protected]> wrote:
> On Tuesday 22 May 2007 20:25, Ingo Molnar wrote:
> > * Con Kolivas <[email protected]> wrote:
> > > > > there was nothing else running on the system - so i suspect the
> > > > > swapin activity flagged 'itself' as some 'other' activity and
> > > > > stopped? The swapins happened in 4 bursts, separated by 5 seconds
> > > > > total idleness.
> > > >
> > > > I've noted burst swapins separated by some seconds of pause in my
> > > > desktop system too (with sp_tester and an idle gnome).
> > >
> > > That really is expected, as just about anything, including journal
> > > writeout, would be enough to put it back to sleep for 5 more seconds.
> >
> > note that nothing like that happened on my system - in the
> > swap-prefetch-off case there was _zero_ IO activity during the sleep
> > period.
>
> Ok, granted it's _very_ conservative. [...]
but your first reaction was "it should not have slept for 5 seconds":
| Hmm.. The timer waits 5 seconds before trying to prefetch, but then
| only stops if it detects any activity elsewhere. It doesn't actually
| try to go idle in between
It clearly should not consider 'itself' as IO activity. This suggests
some bug in the 'detect activity' mechanism, agreed? I'm wondering
whether you are seeing the same problem, or is all swap-prefetch IO on
your system continuous until it's done [or some other IO comes
inbetween]?
The only "problem" I can see with this idea is in the potential case
that it takes up all the IO activity, and so there is never enough IO
activity from other progams to trigger the wait mechanism because they
don't get a chance to run.
That could probably be "fixed" by capping the IO, though... (with one
of those oh-so-lovable "magic numbers" or a tunable)
That said, I don't think there are any issues with the code
compensating for its own activity in the "detect activity" mechanism
-- assuming there wasn't a major impact in e.g. maintainability or
something.
As for the burstyness... considering the "no negative impact" stance,
I can understand that. But it seems inefficient, at best...
--
Michael Chang
Please avoid sending me Word or PowerPoint attachments.
See http://www.gnu.org/philosophy/no-word-attachments.html
Thank you.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
