On Thu, Feb 07, 2008 at 07:04:47PM -0800, Andrew Morton wrote: > On Fri, 8 Feb 2008 02:45:32 +0000 Alasdair G Kergon <[EMAIL PROTECTED]> wrote: > > > dm: move deferred bio flushing to workqueue > > To my unpracticed eye this one looks fairly fundamental. Unfortunately the > changelog: > > Add a single-thread workqueue for each mapped device and move flushing > of the lists of pushback and deferred bios to this new workqueue. > > tells us nothing of the reasons for this change. (It should have done so!) > > It _looks_ pretty unscalable. Perhaps these deferred BIOs don't happen > very often? Indeed - it's a rare occurrence - happens when the dm device is suspended/resumed which usually means it was being reconfigured by something in userspace.
It's the first patch of a series that will provide barrier support (slated for 2.6.26). The appearance of all these workqueues in dm goes back to this old change: md-dm-reduce-stack-usage-with-stacked-block-devices.patch Alasdair -- [EMAIL PROTECTED] -- 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/
