Yang, On 2/3/22 12:12, Yang Shi wrote: > Currently, rasdaemon uses the existing tracepoint block_rq_complete > and filters out non-error cases in order to capture block disk errors. > > But there are a few problems with this approach: > > 1. Even kernel trace filter could do the filtering work, there is > still some overhead after we enable this tracepoint. > > 2. The filter is merely based on errno, which does not align with kernel > logic to check the errors for print_req_error(). > > 3. block_rq_complete only provides dev major and minor to identify > the block device, it is not convenient to use in user-space. > > So introduce a new tracepoint block_rq_error just for the error case. > With this patch, rasdaemon could switch to block_rq_error. > This patch looks good, but I've a question for you. We already have a tracepoint for the request completion block_rq_complete(). We are adding a new tracepoint blk_rq_error() that is also similar to what blk_rq_complete() reports. Similar call sites :- trace_block_rq_complete(req, error, nr_bytes); trace_block_rq_error(req, error, nr_bytes); The only delta between blk_rq_complete() and blk_rq_error() is cmd field for blk_rq_complete() in the TP_STRUCT_ENTRY() and __get_str(cmd) field in TP_printk() which I don't think will have any issue if we use that for blk_rq_error(). Question 1 :- What prevents us from using the same format for both blk_rq_complete() and blk_rq_error() ? Question 2 :- assuming that blk_rq_complete() and blk_rq_error() are using same format why can't we :- declare DECLARE_EVENT_CLASS(blk_rq_completion....) and use that class for blk_rq_complete() and blk_rq_error() ? since if I remember correctly we need to define a event class instead of duplicating a tracepoint with similar reporting. -ck
