linux-kernel - [PATCH v4 2/2] f2fs: add iostat latency statistics support for discard

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Date:   Sat,  8 Apr 2023 01:46:08 +0800
From:   Yangtao Li <frank.li@...o.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <chao@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Yangtao Li <frank.li@...o.com>,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: [PATCH v4 2/2] f2fs: add iostat latency statistics support for discard

In this patch, it adds to account discard latency. This allows us to
track the discard io latency of the system lightweightly after enabling
iostat.

Signed-off-by: Yangtao Li <frank.li@...o.com>
---
v4:
-split it to two patch
 fs/f2fs/f2fs.h              |  1 +
 fs/f2fs/iostat.c            |  6 ++++--
 fs/f2fs/segment.c           |  8 +++++++-
 include/trace/events/f2fs.h | 12 ++++++++++--
 4 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 3d883201e7a5..1779f3596176 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1112,6 +1112,7 @@ enum page_type {
 	META_FLUSH,
 	IPU,		/* the below types are used by tracepoints only. */
 	OPU,
+	DISCARD,	/* used by iostat */
 };
 
 enum temp_type {
diff --git a/fs/f2fs/iostat.c b/fs/f2fs/iostat.c
index 5d496d5b70d3..f40b8915ae1b 100644
--- a/fs/f2fs/iostat.c
+++ b/fs/f2fs/iostat.c
@@ -235,7 +235,7 @@ void iostat_update_and_unbind_ctx(struct bio *bio)
 {
 	struct bio_iostat_ctx *iostat_ctx = bio->bi_private;
 
-	if (op_is_write(bio_op(bio)))
+	if (op_is_write(bio_op(bio)) && !op_is_discard(bio_op(bio)))
 		bio->bi_private = iostat_ctx->sbi;
 	else
 		bio->bi_private = iostat_ctx->iostat_private;
@@ -251,7 +251,9 @@ void iostat_update_submit_ctx(struct bio *bio, enum page_type type)
 
 	iostat_ctx->submit_ts = jiffies;
 
-	if (op_is_write(bio_op(bio))) {
+	if (type == DISCARD) {
+		lat_type = DISCARD_LAT;
+	} else if (op_is_write(bio_op(bio))) {
 		lat_type = bio->bi_opf & REQ_SYNC ?
 				WRITE_SYNC_DATA_LAT : WRITE_ASYNC_DATA_LAT;
 		lat_type = (enum iostat_lat_type)(lat_type + type);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index fc0734e4fb92..be24e9c945a3 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1100,9 +1100,12 @@ static void __remove_discard_cmd(struct f2fs_sb_info *sbi,
 
 static void f2fs_submit_discard_endio(struct bio *bio)
 {
-	struct discard_cmd *dc = (struct discard_cmd *)bio->bi_private;
+	struct discard_cmd *dc;
 	unsigned long flags;
 
+	iostat_update_and_unbind_ctx(bio);
+	dc = bio->bi_private;
+
 	spin_lock_irqsave(&dc->lock, flags);
 	if (!dc->error)
 		dc->error = blk_status_to_errno(bio->bi_status);
@@ -1276,6 +1279,9 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
 		bio->bi_private = dc;
 		bio->bi_end_io = f2fs_submit_discard_endio;
 		bio->bi_opf |= flag;
+
+		iostat_alloc_and_bind_ctx(sbi, bio, dc);
+		iostat_update_submit_ctx(bio, DISCARD);
 		submit_bio(bio);
 
 		atomic_inc(&dcc->issued_discard);
diff --git a/include/trace/events/f2fs.h b/include/trace/events/f2fs.h
index 040a430e1199..385291ac9ad5 100644
--- a/include/trace/events/f2fs.h
+++ b/include/trace/events/f2fs.h
@@ -2078,6 +2078,9 @@ TRACE_EVENT(f2fs_iostat_latency,
 		__field(unsigned int,	m_wr_as_peak)
 		__field(unsigned int,	m_wr_as_avg)
 		__field(unsigned int,	m_wr_as_cnt)
+		__field(unsigned int,	discard_peak)
+		__field(unsigned int,	discard_avg)
+		__field(unsigned int,	discard_cnt)
 	),
 
 	TP_fast_assign(
@@ -2109,6 +2112,9 @@ TRACE_EVENT(f2fs_iostat_latency,
 		__entry->m_wr_as_peak	= iostat_lat[WRITE_ASYNC_META_LAT].peak_lat;
 		__entry->m_wr_as_avg	= iostat_lat[WRITE_ASYNC_META_LAT].avg_lat;
 		__entry->m_wr_as_cnt	= iostat_lat[WRITE_ASYNC_META_LAT].cnt;
+		__entry->discard_peak	= iostat_lat[DISCARD_LAT].peak_lat;
+		__entry->discard_avg	= iostat_lat[DISCARD_LAT].avg_lat;
+		__entry->discard_cnt	= iostat_lat[DISCARD_LAT].cnt;
 	),
 
 	TP_printk("dev = (%d,%d), "
@@ -2116,7 +2122,8 @@ TRACE_EVENT(f2fs_iostat_latency,
 		"rd_data [%u/%u/%u], rd_node [%u/%u/%u], rd_meta [%u/%u/%u], "
 		"wr_sync_data [%u/%u/%u], wr_sync_node [%u/%u/%u], "
 		"wr_sync_meta [%u/%u/%u], wr_async_data [%u/%u/%u], "
-		"wr_async_node [%u/%u/%u], wr_async_meta [%u/%u/%u]",
+		"wr_async_node [%u/%u/%u], wr_async_meta [%u/%u/%u], "
+		"discard [%u/%u/%u]",
 		show_dev(__entry->dev),
 		__entry->d_rd_peak, __entry->d_rd_avg, __entry->d_rd_cnt,
 		__entry->n_rd_peak, __entry->n_rd_avg, __entry->n_rd_cnt,
@@ -2126,7 +2133,8 @@ TRACE_EVENT(f2fs_iostat_latency,
 		__entry->m_wr_s_peak, __entry->m_wr_s_avg, __entry->m_wr_s_cnt,
 		__entry->d_wr_as_peak, __entry->d_wr_as_avg, __entry->d_wr_as_cnt,
 		__entry->n_wr_as_peak, __entry->n_wr_as_avg, __entry->n_wr_as_cnt,
-		__entry->m_wr_as_peak, __entry->m_wr_as_avg, __entry->m_wr_as_cnt)
+		__entry->m_wr_as_peak, __entry->m_wr_as_avg, __entry->m_wr_as_cnt,
+		__entry->discard_peak, __entry->discard_avg, __entry->discard_cnt)
 );
 #endif
 
-- 
2.35.1