From: Daniel Gomez <[email protected]> Report block alignment in terms of LBA and size during block tracing for block_rq. Calculate alignment only for read/writes where the length is greater than 0. Otherwise, report 0 to indicate no alignment calculated.
Suggested-by: Dave Chinner <[email protected]> Signed-off-by: Daniel Gomez <[email protected]> --- This patch introduces LBA and size alignment information for the block_rq tracepoints (block_rq{insert, issue, merge} and block_{io_start, io_done}). The idea of reporting alignment in a tracepoint was first suggested in this thread [1] by Dave Chinner. Additionally, an eBPF-based equivalent tracing tool [2] was developed and used during LBS development, as mentioned in the patch series [3] and in [1]. With this addition, users can check block alignment directly through the block layer tracepoints without needing any additional tools. In case we have a use case, this can be extended to other tracepoints, such as complete and error. Another potential enhancement could be the integration of this information into blktrace. Would that be a feasible option to consider? [1] https://lore.kernel.org/all/zdvxan1q%[email protected]/ [2] blkalgn tool written in eBPF/bcc: https://github.com/dkruces/bcc/tree/lbs [3] https://lore.kernel.org/all/[email protected]/ --- block/blk-mq.c | 29 +++++++++++++++++++++++++++++ include/linux/blk-mq.h | 11 +++++++++++ include/linux/blkdev.h | 6 ++++++ include/trace/events/block.h | 7 +++++-- 4 files changed, 51 insertions(+), 2 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 831c5cf5d874..714452bc236b 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -4920,6 +4920,35 @@ int blk_rq_poll(struct request *rq, struct io_comp_batch *iob, } EXPORT_SYMBOL_GPL(blk_rq_poll); +u32 __blk_rq_lba_algn(struct request *req) +{ + u32 lbs = queue_logical_block_size(req->q); + u32 lba_shift = ilog2(lbs); + u32 lba = req->__sector >> (lba_shift - SECTOR_SHIFT); + u32 len = req->__data_len; + u32 algn_len = len; + u32 algn_lba = len / lbs; + u32 alignment = lbs; + + if (is_power_of_2(len) && + blk_rq_lba_aligned(len, algn_len, lba, algn_lba)) + return len; + + algn_len = lbs << 1U; + algn_lba = algn_len / lbs; + + while (algn_len < len) { + if (!blk_rq_lba_aligned(len, algn_len, lba, algn_lba)) + break; + + alignment = algn_len; + algn_len = algn_len << 1U; + algn_lba = algn_len / lbs; + } + + return alignment; +} + unsigned int blk_mq_rq_cpu(struct request *rq) { return rq->mq_ctx->cpu; diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 8d304b1d16b1..02959fbd5e28 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -740,6 +740,17 @@ void blk_mq_free_request(struct request *rq); int blk_rq_poll(struct request *rq, struct io_comp_batch *iob, unsigned int poll_flags); +/* The alignment of the block in terms of LBA and size */ +u32 __blk_rq_lba_algn(struct request *req); +static inline u32 blk_rq_lba_algn(struct request *req) +{ + if ((req_op(req) != REQ_OP_WRITE) && (req_op(req) != REQ_OP_READ) && + !(req->__data_len)) + return 0; + + return __blk_rq_lba_algn(req); +} + bool blk_mq_queue_inflight(struct request_queue *q); enum { diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index bf1aa951fda2..28557987daa8 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1433,6 +1433,12 @@ static inline int blk_rq_aligned(struct request_queue *q, unsigned long addr, return !(addr & alignment) && !(len & alignment); } +static inline bool blk_rq_lba_aligned(u32 len, u32 algn_len, u32 lba, + u32 algn_lba) +{ + return !(len % algn_len) && !(lba % algn_lba); +} + /* assumes size > 256 */ static inline unsigned int blksize_bits(unsigned int size) { diff --git a/include/trace/events/block.h b/include/trace/events/block.h index 1527d5d45e01..ba3764214dc7 100644 --- a/include/trace/events/block.h +++ b/include/trace/events/block.h @@ -202,6 +202,7 @@ DECLARE_EVENT_CLASS(block_rq, __array( char, rwbs, RWBS_LEN ) __array( char, comm, TASK_COMM_LEN ) __dynamic_array( char, cmd, 1 ) + __field( unsigned int, algn ) ), TP_fast_assign( @@ -210,20 +211,22 @@ DECLARE_EVENT_CLASS(block_rq, __entry->nr_sector = blk_rq_trace_nr_sectors(rq); __entry->bytes = blk_rq_bytes(rq); __entry->ioprio = rq->ioprio; + __entry->algn = blk_rq_lba_algn(rq); blk_fill_rwbs(__entry->rwbs, rq->cmd_flags); __get_str(cmd)[0] = '\0'; memcpy(__entry->comm, current->comm, TASK_COMM_LEN); ), - TP_printk("%d,%d %s %u (%s) %llu + %u %s,%u,%u [%s]", + TP_printk("%d,%d %s %u (%s) %llu + %u %s,%u,%u |%u| [%s]", MAJOR(__entry->dev), MINOR(__entry->dev), __entry->rwbs, __entry->bytes, __get_str(cmd), (unsigned long long)__entry->sector, __entry->nr_sector, __print_symbolic(IOPRIO_PRIO_CLASS(__entry->ioprio), IOPRIO_CLASS_STRINGS), IOPRIO_PRIO_HINT(__entry->ioprio), - IOPRIO_PRIO_LEVEL(__entry->ioprio), __entry->comm) + IOPRIO_PRIO_LEVEL(__entry->ioprio), __entry->algn, + __entry->comm) ); /** --- base-commit: 57f962b956f1d116cd64d5c406776c4975de549d change-id: 20240912-add-blkalgn-block-trace-71e8ab6708f1 Best regards, -- Daniel Gomez <[email protected]>
