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[PATCH 00/11]blktrace: output cgroup info

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  [PATCH 00/11]blktrace: output cgroup info Shaohua Li <shli@kernel.org> - 2017-06-03 00:00 +0200
    [PATCH 11/11] block: use standard blktrace API to output cgroup info for debug notes Shaohua Li <shli@kernel.org> - 2017-06-03 00:00 +0200
      Re: [PATCH 11/11] block: use standard blktrace API to output cgroup  info for debug notes kbuild test robot <lkp@intel.com> - 2017-06-03 03:20 +0200

#1656596 — [PATCH 00/11]blktrace: output cgroup info

From: Shaohua Li <shli@fb.com>

Hi,

Currently blktrace isn't cgroup aware. blktrace prints out task name of current
context, but the task of current context isn't always in the cgroup where the
BIO comes from. We can't use task name to find out IO cgroup. For example,
Writeback BIOs always comes from flusher thread but the BIOs are for different
blk cgroups. Request could be requeued and dispatched from completely different
tasks. MD/DM are another examples. This brings challenges if we want to use
blktrace for performance tunning with cgroup enabled.

This patchset try to fix the gap. We print out cgroup fhandle info in blktrace.
Userspace can use open_by_handle_at() syscall to find the cgroup by fhandle. Or
userspace can use name_to_handle_at() syscall to find fhandle for a cgroup and
use a BPF program to filter out blktrace for a specific cgroup.

The first 5 patches adds export operation handlers for kernfs, so userspace can
use open_by_handle_at/name_to_handle_at to a kernfs file. Later patches make
blktrace output cgroup info.

Thanks,
Shaohua

Shaohua Li (11):
  kernfs: implement i_generation
  kernfs: use idr instead of ida to manage inode number
  kernfs: add an API to get kernfs node from inode number
  kernfs: don't set dentry->d_fsdata
  kernfs: add exportfs operations
  cgroup: export fhandle info for a cgroup
  blktrace: export cgroup info in trace
  block: always attach cgroup info into bio
  block: call __bio_free in bio_endio
  blktrace: add an option to allow displying cgroup path
  block: use standard blktrace API to output cgroup info for debug notes

 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c |   2 +-
 block/bfq-iosched.h                      |  16 +-
 block/bio-integrity.c                    |   1 +
 block/bio.c                              |   1 +
 block/blk-throttle.c                     |  13 +-
 block/cfq-iosched.c                      |  15 +-
 fs/kernfs/dir.c                          |  80 +++++++---
 fs/kernfs/file.c                         |   6 +-
 fs/kernfs/inode.c                        |   7 +-
 fs/kernfs/kernfs-internal.h              |   4 +
 fs/kernfs/mount.c                        | 107 +++++++++++--
 fs/kernfs/symlink.c                      |   6 +-
 fs/sysfs/mount.c                         |   2 +-
 include/linux/blk-cgroup.h               |  16 +-
 include/linux/blktrace_api.h             |  12 +-
 include/linux/cgroup-defs.h              |   2 +
 include/linux/cgroup.h                   |  14 ++
 include/linux/kernfs.h                   |  23 ++-
 include/uapi/linux/blktrace_api.h        |   3 +
 kernel/cgroup/cgroup.c                   |  18 ++-
 kernel/trace/blktrace.c                  | 254 +++++++++++++++++++++----------
 21 files changed, 430 insertions(+), 172 deletions(-)

-- 
2.9.3

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#1656598 — [PATCH 11/11] block: use standard blktrace API to output cgroup info for debug notes

From: Shaohua Li <shli@fb.com>

Currently cfq/bfq/blk-throttle output cgroup info in trace in their own
way. Now we have standard blktrace API for this, so convert them to use
it.

Note, this changes the behavior a little bit. cgroup info isn't output
by default, we only do this with 'blk_cgroup' option enabled. cgroup
info isn't output as a string by default too, we only do this with
'blk_cgname' option enabled. Also cgroup info is output in different
position of the note string. I think these behavior changes aren't a big
issue (actually we make trace data shorter which is good), since the
blktrace note is solely for debugging.

Signed-off-by: Shaohua Li <shli@fb.com>
---
 block/bfq-iosched.h          | 16 ++++++----------
 block/blk-throttle.c         |  6 ++----
 block/cfq-iosched.c          | 15 ++++++---------
 include/linux/blk-cgroup.h   | 14 --------------
 include/linux/blktrace_api.h | 12 ++++++++----
 kernel/trace/blktrace.c      | 10 +++++++---
 6 files changed, 29 insertions(+), 44 deletions(-)

diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index ae783c0..e4d5b56 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -910,19 +910,15 @@ void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq);
 struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
 
 #define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
-	char __pbuf[128];						\
-									\
-	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
-	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, (bfqq)->pid, \
-			bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
-			  __pbuf, ##args);				\
+	blk_add_cgroup_trace_msg((bfqd)->queue,				\
+			bfqg_to_blkg(bfqq_group(bfqq))->blkcg,		\
+			"bfq%d%c " fmt, (bfqq)->pid,			\
+			bfq_bfqq_sync((bfqq)) ? 'S' : 'A', ##args);	\
 } while (0)
 
 #define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
-	char __pbuf[128];						\
-									\
-	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
-	blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args);	\
+	blk_add_cgroup_trace_msg((bfqd)->queue,				\
+		bfqg_to_blkg(bfqg)->blkcg, fmt, ##args);		\
 } while (0)
 
 #else /* CONFIG_BFQ_GROUP_IOSCHED */
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 53d3e3d..46e85e0 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -352,10 +352,8 @@ static unsigned int tg_iops_limit(struct throtl_grp *tg, int rw)
 	if (likely(!blk_trace_note_message_enabled(__td->queue)))	\
 		break;							\
 	if ((__tg)) {							\
-		char __pbuf[128];					\
-									\
-		blkg_path(tg_to_blkg(__tg), __pbuf, sizeof(__pbuf));	\
-		blk_add_trace_msg(__td->queue, "throtl %s " fmt, __pbuf, ##args); \
+		blk_add_cgroup_trace_msg(__td->queue,			\
+			tg_to_blkg(__tg)->blkcg, "throtl " fmt, ##args);\
 	} else {							\
 		blk_add_trace_msg(__td->queue, "throtl " fmt, ##args);	\
 	}								\
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index da69b07..5f59f37 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -652,20 +652,17 @@ static inline void cfqg_put(struct cfq_group *cfqg)
 }
 
 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...)	do {			\
-	char __pbuf[128];						\
-									\
-	blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf));	\
-	blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c %s " fmt, (cfqq)->pid, \
+	blk_add_cgroup_trace_msg((cfqd)->queue,				\
+			cfqg_to_blkg((cfqq)->cfqg)->blkcg,		\
+			"cfq%d%c%c " fmt, (cfqq)->pid,			\
 			cfq_cfqq_sync((cfqq)) ? 'S' : 'A',		\
 			cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
-			  __pbuf, ##args);				\
+			  ##args);					\
 } while (0)
 
 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...)	do {			\
-	char __pbuf[128];						\
-									\
-	blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf));		\
-	blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args);	\
+	blk_add_cgroup_trace_msg((cfqd)->queue,				\
+			cfqg_to_blkg(cfqg)->blkcg, fmt, ##args);	\
 } while (0)
 
 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index d176247..b06f107 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -334,19 +334,6 @@ static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
 }
 
 /**
- * blkg_path - format cgroup path of blkg
- * @blkg: blkg of interest
- * @buf: target buffer
- * @buflen: target buffer length
- *
- * Format the path of the cgroup of @blkg into @buf.
- */
-static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
-{
-	return cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
-}
-
-/**
  * blkg_get - get a blkg reference
  * @blkg: blkg to get
  *
@@ -758,7 +745,6 @@ static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 						  struct blkcg_policy *pol) { return NULL; }
 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
-static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
 static inline void blkg_get(struct blkcg_gq *blkg) { }
 static inline void blkg_put(struct blkcg_gq *blkg) { }
 
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index d2e9085..cbfadd0 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -28,10 +28,12 @@ struct blk_trace {
 	atomic_t dropped;
 };
 
+struct blkcg;
+
 extern int blk_trace_ioctl(struct block_device *, unsigned, char __user *);
 extern void blk_trace_shutdown(struct request_queue *);
-extern __printf(2, 3)
-void __trace_note_message(struct blk_trace *, const char *fmt, ...);
+extern __printf(3, 4)
+void __trace_note_message(struct blk_trace *, struct blkcg *blkcg, const char *fmt, ...);
 
 /**
  * blk_add_trace_msg - Add a (simple) message to the blktrace stream
@@ -46,12 +48,14 @@ void __trace_note_message(struct blk_trace *, const char *fmt, ...);
  *     NOTE: Can not use 'static inline' due to presence of var args...
  *
  **/
-#define blk_add_trace_msg(q, fmt, ...)					\
+#define blk_add_cgroup_trace_msg(q, cg, fmt, ...)			\
 	do {								\
 		struct blk_trace *bt = (q)->blk_trace;			\
 		if (unlikely(bt))					\
-			__trace_note_message(bt, fmt, ##__VA_ARGS__);	\
+			__trace_note_message(bt, cg, fmt, ##__VA_ARGS__);\
 	} while (0)
+#define blk_add_trace_msg(q, fmt, ...)					\
+	blk_add_cgroup_trace_msg(q, NULL, fmt, ##__VA_ARGS__)
 #define BLK_TN_MAX_MSG		128
 
 static inline bool blk_trace_note_message_enabled(struct request_queue *q)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 18cbc02..9e135dd 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -154,7 +154,8 @@ static void trace_note_time(struct blk_trace *bt)
 	local_irq_restore(flags);
 }
 
-void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
+void __trace_note_message(struct blk_trace *bt, struct blkcg *blkcg,
+	const char *fmt, ...)
 {
 	int n;
 	va_list args;
@@ -178,7 +179,10 @@ void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
 	n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
 	va_end(args);
 
-	trace_note(bt, 0, BLK_TN_MESSAGE, buf, n, NULL);
+	if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
+		blkcg = NULL;
+	trace_note(bt, 0, BLK_TN_MESSAGE, buf, n,
+		blkcg ? cgroup_get_node_id(blkcg->css.cgroup) : NULL);
 	local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(__trace_note_message);
@@ -375,7 +379,7 @@ static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
 		return PTR_ERR(msg);
 
 	bt = filp->private_data;
-	__trace_note_message(bt, "%s", msg);
+	__trace_note_message(bt, NULL, "%s", msg);
 	kfree(msg);
 
 	return count;
-- 
2.9.3

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#1656655 — Re: [PATCH 11/11] block: use standard blktrace API to output cgroup info for debug notes

[Multipart message — attachments visible in raw view] — view raw

Hi Shaohua,

[auto build test ERROR on driver-core/driver-core-testing]
[also build test ERROR on v4.12-rc3 next-20170602]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Shaohua-Li/kernfs-implement-i_generation/20170603-083132
config: x86_64-randconfig-x010-201722 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   kernel/trace/blktrace.c: In function '__trace_note_message':
>> kernel/trace/blktrace.c:185:35: error: 'struct blkcg' has no member named 'css'
      blkcg ? cgroup_get_node_id(blkcg->css.cgroup) : NULL);
                                      ^~

vim +185 kernel/trace/blktrace.c

   179		n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
   180		va_end(args);
   181	
   182		if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
   183			blkcg = NULL;
   184		trace_note(bt, 0, BLK_TN_MESSAGE, buf, n,
 > 185			blkcg ? cgroup_get_node_id(blkcg->css.cgroup) : NULL);
   186		local_irq_restore(flags);
   187	}
   188	EXPORT_SYMBOL_GPL(__trace_note_message);

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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