On Tue, Jul 20, 2021 at 08:57:06AM +0200, Christoph Hellwig wrote: > On Mon, Jul 19, 2021 at 07:39:52PM +0100, Matthew Wilcox (Oracle) wrote: > > All but one caller already has the iomap_page, and we can avoid getting > > it again. > > > > Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> > > Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx> > > In general reloading it from a single pointer should be faster than > passing an extra argument. What is the rationale here? I'm not sure we can make that determination in general; it's going to depend on the number of registers the CPU has, the calling conventions, how much inlining the compiler chooses to do, etc. The compiler is actually _forced_ to reload the iop from the page by the test_bit() in PagePrivate() / folio_test_private(). I want to kill off that bit, but until I have time to work on that, we don't have a good workaround.
