Re: [PATCH 2/2] mirror throttling
From: Alasdair G Kergon
Date: Thu Feb 14 2013 - 19:53:30 EST
On Wed, Jan 09, 2013 at 12:44:38AM -0500, Mikulas Patocka wrote:
> We maintain a history of kcopyd usage in variables io_period and
> total_period. The actual kcopyd activity is "(100 * io_period /
> total_period)" percent of time. If we exceed user-defined percentage
> threshold, we sleep.
Well, I'm going to take this pair of patches for now.
Some people do need this throttling today and this seems to me to be a
decent and simple way to give them a lever to deal with the problem.
I'm not proposing we expose this through LVM or other userspace tools at
this stage: people who need it should tune it directly through sysfs.
If need be, we can revisit this in future either by refining the
algorithm or making it adjustable per-device rather than per-module.
(Or by re-vamping kcopyd itself...)
The current version is:
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/