Re: Workaround for wrapping loadaverage
From: Patrick Mau
Date: Mon Nov 08 2004 - 19:45:21 EST
On Mon, Nov 08, 2004 at 03:50:51PM -0800, Andrew Morton wrote:
> (PLease don't remove people from Cc:. Just do reply-to-all).
sorry, I usually remove people from CC if they're subscribed.
> Patrick Mau <mau@xxxxxxxxxxxxx> wrote:
> > If you would use 236, 252 and 255 the last to load calculations would
> > get optimized into register shifts during calculation. The precision
> > would be bad, but I personally don't mind loosing the fraction.
> What would be the impact on the precision if we were to use 8 bits of
I didn't have time to check again, but I think I ended up with a load of 0.97
using one runnable process because of rounding errors.
> An upper limit of 1024 tasks sounds a bit squeezy. Even 8192 is a bit
> uncomfortable. Maybe we should just reimplement the whole thing, perhaps
> in terms of tuples of 32-bit values: 32 bits each side of the binary point?
We re-calculate the load every 5 seconds. I think it would be OK to
use more bits/registers, it's not that frequently called.
It's 1:30 AM and I had a rough working day, maybe I'll prepare a little patch
tomorrow. I think that 8192 _runnable_ processes seems a bit unusual, but we
also account for uninterruptable processes. Maybe there was some swap/IO
storm that triggered the initial overflow, I'll have to check that first.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/