Re: [Crash-utility] [PATCH 1/2] Support for "dev -d|-D" options by parsing bitmap in blk-mq layer

> - Is it possible to use the new logic when blk-mq has sbitmap, even if > a kernel has rq_dispatched and rq_completed? > > > > If we would like to replace the rq_dispatched/rq_completed with the sbitmap > to calculate the disk I/O statistics, that might be extra work. > > But anyway, if it's worth doing, we might consider doing it at the next stage. > What do you think? sorry, cannot get it. I just mean this flow: if blk-mq uses sbitmap then get_mq_diskio_from_hw_queues(q, &tmp); return; else if rq_dispatched/rq_completed exists then ... get_one_mctx_diskio(mctx_addr, &tmp); It means that crash will preferentially use the sbitmap to calculate the disk I/O statistics since kernel started to introduce the sbitmap for the blk-mq feature.

What is the extra work? The extra work is that: crash has to support parsing sbitmap on old kernel, and need to follow up the relevant kernel structure changes, it will make the implementation of the get_mq_diskio_from_hw_queues() become more complex. That is my concern.