Re: [PATCH 08/17] blkcg: shoot down blkio_groups on elevator switch

From: Vivek Goyal
Date: Mon Jan 23 2012 - 16:03:33 EST


On Mon, Jan 23, 2012 at 12:47:57PM -0800, Tejun Heo wrote:
> Hello, Lennart.
>
> On Mon, Jan 23, 2012 at 09:43:52PM +0100, Lennart Poettering wrote:
> > I didn't really follow the whole discussion here, but if this is about
> > adjusting parameters of a block device as the block device shows up this
> > must necessarily happen in an udev rule (and not in a daemon watching
> > block devices using libudev), since you most likely need the
> > synchronicity: i.e. you want to avoid that normal (libudev-using)
> > userspace code ever sees the device before those params are written to
> > the device. A daemon asynchronously watching the devices with libudev
> > for adjusting such tunables is necessarily racy.
>
> Yeap, this needs to be synchronous so that it's configured before the
> rest of system notices the device. Vivek, can you please ask the
> tuned guys to take a look?

Sure I will. Thanks.

Vivek
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