On Fri, Oct 18, 2024 at 4:00 AM Yunsheng Lin <linyunsheng@xxxxxxxxxx> wrote: > > Currently there is one 'struct page_frag' for every 'struct > sock' and 'struct task_struct', we are about to replace the > 'struct page_frag' with 'struct page_frag_cache' for them. > Before begin the replacing, we need to ensure the size of > 'struct page_frag_cache' is not bigger than the size of > 'struct page_frag', as there may be tens of thousands of > 'struct sock' and 'struct task_struct' instances in the > system. > > By or'ing the page order & pfmemalloc with lower bits of > 'va' instead of using 'u16' or 'u32' for page size and 'u8' > for pfmemalloc, we are able to avoid 3 or 5 bytes space waste. > And page address & pfmemalloc & order is unchanged for the > same page in the same 'page_frag_cache' instance, it makes > sense to fit them together. > > After this patch, the size of 'struct page_frag_cache' should be > the same as the size of 'struct page_frag'. > > CC: Alexander Duyck <alexander.duyck@xxxxxxxxx> > Signed-off-by: Yunsheng Lin <linyunsheng@xxxxxxxxxx> > --- > include/linux/mm_types_task.h | 19 +++++---- > include/linux/page_frag_cache.h | 24 ++++++++++- > mm/page_frag_cache.c | 70 ++++++++++++++++++++++----------- > 3 files changed, 81 insertions(+), 32 deletions(-) > LGTM Reviewed-by: Alexander Duyck <alexanderduyck@xxxxxx>
