Apologies for the top posting. +Ryan, I missed adding Ryan at the last moment :-) On Thu, Mar 28, 2024 at 10:48 AM Barry Song <21cnbao@xxxxxxxxx> wrote: > > From: Barry Song <v-songbaohua@xxxxxxxx> > > mTHP is generally considered to potentially waste memory due to fragmentation, > but it may also serve as a source of memory savings. > When large folios are compressed at a larger granularity, we observe a remarkable > decrease in CPU utilization and a significant improvement in compression ratios. > > The following data illustrates the time and compressed data for typical anonymous > pages gathered from Android phones. > > granularity orig_data_size compr_data_size time(us) > 4KiB-zstd 1048576000 246876055 50259962 > 64KiB-zstd 1048576000 199763892 18330605 > > Due to mTHP's ability to be swapped out without splitting[1] and swapped in as a > whole[2], it enables compression and decompression to be performed at larger > granularities. > > This patchset enhances zsmalloc and zram by introducing support for dividing large > folios into multi-pages, typically configured with a 4-order granularity. Here are > concrete examples: > > * If a large folio's size is 32KiB, it will still be compressed and stored at a 4KiB > granularity. > * If a large folio's size is 64KiB, it will be compressed and stored as a single 64KiB > block. > * If a large folio's size is 128KiB, it will be compressed and stored as two 64KiB > multi-pages. > > Without the patchset, a large folio is always divided into nr_pages 4KiB blocks. > > The granularity can be configured using the ZSMALLOC_MULTI_PAGES_ORDER setting. > > [1] https://lore.kernel.org/linux-mm/20240327144537.4165578-1-ryan.roberts@xxxxxxx/ > [2] https://lore.kernel.org/linux-mm/20240304081348.197341-1-21cnbao@xxxxxxxxx/ > > Tangquan Zheng (2): > mm: zsmalloc: support objects compressed based on multiple pages > zram: support compression at the granularity of multi-pages > > drivers/block/zram/Kconfig | 9 + > drivers/block/zram/zcomp.c | 23 ++- > drivers/block/zram/zcomp.h | 12 +- > drivers/block/zram/zram_drv.c | 372 +++++++++++++++++++++++++++++++--- > drivers/block/zram/zram_drv.h | 21 ++ > include/linux/zsmalloc.h | 10 +- > mm/Kconfig | 18 ++ > mm/zsmalloc.c | 215 +++++++++++++++----- > 8 files changed, 586 insertions(+), 94 deletions(-) > > -- > 2.34.1 >
