On Mon, May 10, 2021 at 11:58:32PM -0700, Song Liu wrote:
> IIUC, the sysfs node is needed to get better performance (by disabling
> accounting)?
FYI, we already have that sysfs file in the block layer
("queue/iostats"), please just observe QUEUE_FLAG_IO_STAT flag.
> in md.c). This
> should simplify the code. If the user do not need extreme performance, we should
> keep the stats on (default). If the user do need extreme performance, s/he could
> disable stats via sysfs.
Given that the code already does a memory allocation it might as well
always clone and do away with the separate md_io allocation entirely.
Memory usage grows a bit, but it can reuse all the bio cloning
infrastructure.
