On 18-11-05 13:19:56, Alexander Duyck wrote: > This patch modifies the set_page_links function to include the setting of > the reserved flag via a simple AND and OR operation. The motivation for > this is the fact that the existing __set_bit call still seems to have > effects on performance as replacing the call with the AND and OR can reduce > initialization time. > > Looking over the assembly code before and after the change the main > difference between the two is that the reserved bit is stored in a value > that is generated outside of the main initialization loop and is then > written with the other flags field values in one write to the page->flags > value. Previously the generated value was written and then then a btsq > instruction was issued. > > On my x86_64 test system with 3TB of persistent memory per node I saw the > persistent memory initialization time on average drop from 23.49s to > 19.12s per node. > > Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx> Reviewed-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
