On Thu, May 23, 2024 at 07:46:25PM +0200, Mikulas Patocka wrote: > Hi > > Here I'm resending the patch, with more comments and explanations added. > > Mikulas > > > From: Mikulas Patocka <mpatocka@xxxxxxxxxx> > > Device mapper sends flush bios to all the targets and the targets send it > to the underlying device. That may be inefficient, for example if a table > contains 10 linear targets pointing to the same physical device, then > device mapper would send 10 flush bios to that device - despite the fact > that only one bio would be sufficient. > > This commit optimizes the flush behavior. It introduces a per-target > variable flush_bypasses_map - it is set when the target supports flush > optimization - currently, the dm-linear and dm-stripe targets support it. > When all the targets in a table have flush_bypasses_map, > flush_bypasses_map on the table is set. __send_empty_flush tests if the > table has flush_bypasses_map - and if it has, no flush bios are sent to > the targets via the "map" method and the list dm_table->devices is > iterated and the flush bios are sent to each member of the list. > > Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> > Suggested-by: Yang Yang <yang.yang@xxxxxxxx> Nicely done, please feel free to stage for 6.11 (create a new 'dm-6.11' branch starting from 'dm-6.10' -- we'll need to rebase dm-6.11 to 6.10-rc2 or so but at least we'll get this commit in the pipeline, push to 'for-next'). Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
