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 <agk@xxxxxxxxxx> 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 -- agk@xxxxxxxxxx -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
