On Mon, Nov 26, 2018 at 12:54:46PM -0800, Andrew Morton wrote: > On Mon, 26 Nov 2018 17:28:13 +0900 Minchan Kim <minc...@kernel.org> wrote: > > > On small memory system, there are lots of write IO so if we use > > flash device as swap, there would be serious flash wearout. > > To overcome the problem, system developers need to design write > > limitation strategy to guarantee flash health for entire product life. > > > > This patch creates a new konb "writeback_limit" on zram. With that, > > if current writeback IO count(/sys/block/zramX/io_stat) excceds > > the limitation, zram stops further writeback until admin can reset > > the limit. > > > > +++ b/Documentation/ABI/testing/sysfs-block-zram > > @@ -121,3 +121,12 @@ Contact: Minchan Kim <minc...@kernel.org> > > The bd_stat file is read-only and represents backing device's > > statistics (bd_count, bd_reads, bd_writes) in a format > > similar to block layer statistics file format. > > + > > +What: /sys/block/zram<id>/writeback_limit > > +Date: November 2018 > > +Contact: Minchan Kim <minc...@kernel.org> > > +Description: > > + The writeback_limit file is read-write and specifies the maximum > > + amount of writeback ZRAM can do. The limit could be changed > > + in run time and "0" means disable the limit. > > + No limit is the initial state. > > diff --git a/Documentation/blockdev/zram.txt > > b/Documentation/blockdev/zram.txt > > index 550bca77d322..41748d52712d 100644 > > --- a/Documentation/blockdev/zram.txt > > +++ b/Documentation/blockdev/zram.txt > > @@ -164,6 +164,8 @@ reset WO trigger device reset > > mem_used_max WO reset the `mem_used_max' counter (see later) > > mem_limit WO specifies the maximum amount of memory ZRAM can use > > to store the compressed data > > +writeback_limit WO specifies the maximum amount of write IO zram > > can > > + write out to backing device > > Neither the changelog nor the Documentation specify the units of > writeback_limit. Bytes? Pages? Blocks? > > This gets so confusing that in many /proc/sys/vm files we actually put > the units into the filenames. >
I will use unit as 4K. Thanks.
