kernel/linux.git/include/trace/events/block.h, branch v7.2-rc1

blk-mq: add tracepoint block_rq_tag_wait

2026-05-26T17:01:54+00:00

In high-performance storage environments, particularly when utilising RAID controllers with shared tag sets (BLK_MQ_F_TAG_HCTX_SHARED), severe latency spikes can occur when fast devices (SSDs) are starved of hardware tags when sharing the same blk_mq_tag_set. Currently, diagnosing this specific hardware queue contention is difficult. When a CPU thread exhausts the tag pool, blk_mq_get_tag() forces the current thread to block uninterruptible via io_schedule(). While this can be inferred via sched:sched_switch or dynamically traced by attaching a kprobe to blk_mq_mark_tag_wait(), there is no dedicated, out-of-the-box observability for this event. This patch introduces the block_rq_tag_wait tracepoint in the tag allocation slow-path. It triggers immediately before the task state is altered to TASK_UNINTERRUPTIBLE (ensuring safety for PREEMPT_RT locks). It exposes the exact hardware context (hctx) that is starved, the specific pool experiencing starvation (driver, software scheduler, or reserved), and the exact pool depth. This provides storage engineers with a zero-configuration, low-overhead mechanism to definitively identify shared-tag bottlenecks. For example, userspace can trivially replicate tag starvation counters using bpftrace: # bpftrace -e 'tracepoint:block:block_rq_tag_wait { @tag_waits[cpu] = count(); }' Attaching 1 probe... ^C @tag_waits[4]: 12 @tag_waits[12]: 87 Signed-off-by: Aaron Tomlin Link: https://patch.msgid.link/20260525005123.722277-1-atomlin@atomlin.com Signed-off-by: Jens Axboe

block: fix blk_zone_append_update_request_bio() kernel-doc

2025-07-16T16:02:18+00:00

Stephen reported new 'make htmldocs' warnings introduced by 4cc21a00762b ("block: add tracepoint for blk_zone_update_request_bio"). One is a wrong function name in the tracepoint's kernel-doc and one is a wrong function parameter. Fix these so 'make htmldocs' is warning free again for the block layer tracepoints. Fixes: 4cc21a00762b ("block: add tracepoint for blk_zone_update_request_bio") Reported-by: Stephen Rothwell Signed-off-by: Johannes Thumshirn Link: https://lore.kernel.org/r/20250716133631.94898-1-johannes.thumshirn@wdc.com Signed-off-by: Jens Axboe

block: add trace messages to zone write plugging

2025-07-15T14:03:49+00:00

Add tracepoints to zone write plugging plug and unplug events. Examples for these events are: kworker/u10:4-393 [001] d..1. 282.991660: disk_zone_wplug_add_bio: 8,0 zone 16, BIO 8388608 + 128 kworker/0:1H-58 [ [000] d..1. 283.083294: blk_zone_wplug_bio: 8,0 zone 15, BIO 7864320 + 128 Reviewed-by: Chaitanya Kulkarni Signed-off-by: Johannes Thumshirn Link: https://lore.kernel.org/r/20250715115324.53308-6-johannes.thumshirn@wdc.com Signed-off-by: Jens Axboe

block: add tracepoint for blkdev_zone_mgmt

2025-07-15T14:03:49+00:00

Add a tracepoint for blkdev_zone_mgmt to trace zone management commands submitted by higher layers like file systems or user space. An example output for this tracepoint is as follows: mkfs.btrfs-203 [001] ..... 42.877493: blkdev_zone_mgmt: 8,0 ZRS 5242880 + 0 This example output shows a REQ_OP_ZONE_RESET operation submitted by mkfs.btrfs. Reviewed-by: Damien Le Moal Reviewed-by: Christoph Hellwig Reviewed-by: Chaitanya Kulkarni Reviewed-by: Bart Van Assche Signed-off-by: Johannes Thumshirn Link: https://lore.kernel.org/r/20250715115324.53308-5-johannes.thumshirn@wdc.com Signed-off-by: Jens Axboe

block: add tracepoint for blk_zone_update_request_bio

2025-07-15T14:03:49+00:00

Add a tracepoint in blk_zone_update_request_bio() to trace the bio sector update on ZONE APPEND completions. An example for this tracepoint is as follows: -0 [001] d.h1. 381.746444: blk_zone_update_request_bio: 259,5 ZAS 131072 () 1048832 + 256 none,0,0 [swapper/1] Reviewed-by: Damien Le Moal Reviewed-by: Christoph Hellwig Reviewed-by: Chaitanya Kulkarni Reviewed-by: Bart Van Assche Signed-off-by: Johannes Thumshirn Link: https://lore.kernel.org/r/20250715115324.53308-4-johannes.thumshirn@wdc.com Signed-off-by: Jens Axboe

blktrace: add zoned block commands to blk_fill_rwbs

2025-07-15T14:03:48+00:00

Add zoned block commands to blk_fill_rwbs: - ZONE APPEND will be decoded as 'ZA' - ZONE RESET will be decoded as 'ZR' - ZONE RESET ALL will be decoded as 'ZRA' - ZONE FINISH will be decoded as 'ZF' - ZONE OPEN will be decoded as 'ZO' - ZONE CLOSE will be decoded as 'ZC' Reviewed-by: Chaitanya Kulkarni Signed-off-by: Johannes Thumshirn Link: https://lore.kernel.org/r/20250715115324.53308-2-johannes.thumshirn@wdc.com Signed-off-by: Jens Axboe

traceevent/block: Add REQ_ATOMIC flag to block trace events

2025-05-23T15:18:48+00:00

Filesystems like XFS can implement atomic write I/O using either REQ_ATOMIC flag set in the bio or via CoW operation. It will be useful if we have a flag in trace events to distinguish between the two. This patch adds char 'U' (Untorn writes) to rwbs field of the trace events if REQ_ATOMIC flag is set in the bio. ================= xfs_io-4238 [009] ..... 4148.126843: block_rq_issue: 259,0 WFSU 16384 () 768 + 32 none,0,0 [xfs_io] -0 [009] d.h1. 4148.129864: block_rq_complete: 259,0 WFSU () 768 + 32 none,0,0 [0] =============== xfs_io-4237 [010] ..... 4143.325616: block_rq_issue: 259,0 WS 16384 () 768 + 32 none,0,0 [xfs_io] -0 [010] d.H1. 4143.329138: block_rq_complete: 259,0 WS () 768 + 32 none,0,0 [0] Signed-off-by: Ritesh Harjani (IBM) Reviewed-by: Ojaswin Mujoo Link: https://lore.kernel.org/r/44317cb2ec4588f6a2c1501a96684e6a1196e8ba.1747921498.git.ritesh.list@gmail.com Signed-off-by: Jens Axboe

block: remove bounce buffering support

2025-05-05T19:22:39+00:00

The block layer bounce buffering support is unused now, remove it. Signed-off-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Reviewed-by: John Garry Reviewed-by: Johannes Thumshirn Link: https://lore.kernel.org/r/20250505081138.3435992-7-hch@lst.de Signed-off-by: Jens Axboe

block: remove the ioprio field from struct request

2024-11-12T21:42:02+00:00

The request ioprio is only initialized from the first attached bio, so requests without a bio already never set it. Directly use the bio field instead. Signed-off-by: Christoph Hellwig Reviewed-by: Bart Van Assche Link: https://lore.kernel.org/r/20241112170050.1612998-3-hch@lst.de Signed-off-by: Jens Axboe

block: Add ioprio to block_rq tracepoint

2024-06-28T16:30:47+00:00

Sometimes we need to track the processing order of requests with ioprio set. So the ioprio of request can be useful information. Example： block_rq_insert: 8,0 RA 16384 () 6500840 + 32 be,0,6 [binder:815_3] block_rq_issue: 8,0 RA 16384 () 6500840 + 32 be,0,6 [binder:815_3] block_rq_complete: 8,0 RA () 6500840 + 32 be,0,6 [0] Signed-off-by: Dongliang Cui Reviewed-by: Bart Van Assche Reviewed-by: Chaitanya Kulkarni Link: https://lore.kernel.org/r/20240614074936.113659-1-dongliang.cui@unisoc.com Signed-off-by: Jens Axboe