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Date: Mon, 27 Apr 2026 12:38:48 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Aaron Tomlin <atomlin@atomlin.com>
Cc: axboe@kernel.dk, mhiramat@kernel.org, mathieu.desnoyers@efficios.com,
 bvanassche@acm.org, johannes.thumshirn@wdc.com, kch@nvidia.com,
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 neelx@suse.com, sean@ashe.io, mproche@gmail.com, chjohnst@gmail.com,
 linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH v5 1/2] blk-mq: add tracepoint block_rq_tag_wait
Message-ID: <20260427123848.1e6b63d2@gandalf.local.home>
In-Reply-To: <20260427020142.358912-2-atomlin@atomlin.com>
References: <20260427020142.358912-1-atomlin@atomlin.com>
	<20260427020142.358912-2-atomlin@atomlin.com>
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On Sun, 26 Apr 2026 22:01:41 -0400
Aaron Tomlin <atomlin@atomlin.com> wrote:

> +TRACE_EVENT(block_rq_tag_wait,
> +
> +	TP_PROTO(struct request_queue *q, struct blk_mq_hw_ctx *hctx, bool is_sched_tag),
> +
> +	TP_ARGS(q, hctx, is_sched_tag),
> +
> +	TP_STRUCT__entry(
> +		__field( dev_t,		dev			)
> +		__field( u32,		hctx_id			)
> +		__field( u32,		nr_tags			)
> +		__field( bool,		is_sched_tag		)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->dev		= q->disk ? disk_devt(q->disk);

Hmm, does the above even compile?

-- Steve

> +		__entry->hctx_id	= hctx->queue_num;
> +		__entry->is_sched_tag	= is_sched_tag;
> +
> +		if (is_sched_tag)
> +			__entry->nr_tags = hctx->sched_tags->nr_tags;
> +		else
> +			__entry->nr_tags = hctx->tags->nr_tags;
> +	),
> +
> +	TP_printk("%d,%d hctx=%u starved on %s tags (depth=%u)",
> +		  MAJOR(__entry->dev), MINOR(__entry->dev),
> +		  __entry->hctx_id,
> +		  __entry->is_sched_tag ? "scheduler" : "hardware",
> +		  __entry->nr_tags)
> +);
> +