On Wed, May 06, 2020 at 04:37:41PM +0800, Jason Wang wrote: > > On 2020/5/6 下午4:08, Michael S. Tsirkin wrote: > > So for mergeable bufs, we use ewma machinery to guess the correct buffer > > size. If we don't guess correctly, XDP has to do aggressive copies. > > > > Problem is, xdp paths do not update the ewma at all, except > > sometimes with XDP_PASS. So whatever we happen to have > > before we attach XDP, will mostly stay around. > > > It looks ok to me since we always use PAGE_SIZE when XDP is enabled in > get_mergeable_buf_len()? > > Thanks > Oh right. Good point! Answered in another thread. > > > > The fix is probably to update ewma unconditionally. > >
