Subject: [PATCH] [FEAT RTL1601] dbginfo.sh: Make use of sysfs collection helper
From: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>

Summary:     dbginfo.sh: Make use of sysfs collection helper
Description: If available, use dump2tar in dbginfo.sh for sysfs
             file collection to significantly speed up dbginfo.sh
             processing. Example speedup on an LPAR with ~190k
             sysfs files:
             
             Unpatched:
               # time ./dbginfo.sh
               real    1m19.624s
               user    0m44.985s
               sys     0m45.173s
             
             Patched:
               # time ./dbginfo.sh
               real    0m5.822s
               user    0m4.523s
               sys     0m2.636s
Upstream-ID: -
Problem-ID:  RTL1601

Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
---
 scripts/dbginfo.sh |   33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

--- a/scripts/dbginfo.sh
+++ b/scripts/dbginfo.sh
@@ -620,20 +620,29 @@ collect_sysfs() {
 	    fi
 	fi
 
-	call_run_command "find /sys -print0 | sort -z | xargs -0 -n 10 ls -ld" "${OUTPUT_FILE_SYSFS}"
+	# Collect sysfs files using multiple threads (-J 1) while excluding
+	# files known to block on read (-x). Stop reading a file that takes
+	# more than 5 seconds (-T 5) such as an active ftrace buffer.
+	dump2tar /sys -z -o "${WORKPATH}/sysfs.tgz" -x '*/tracing/trace_pipe*' \
+		 -x '*/tracing/per_cpu/*' --ignore-failed-read -J 1 -T 5
 
-	find /sys -noleaf -type d 2>/dev/null | while IFS= read -r dir_name; do
-	    mkdir -p "${WORKPATH}${dir_name}"
-	done
+	if [ $? -ne 0 ] ; then
+	    echo "${SCRIPTNAME}: Warning: dump2tar failed or is unavailable - falling back to slow path"
+	    call_run_command "find /sys -print0 | sort -z | xargs -0 -n 10 ls -ld" "${OUTPUT_FILE_SYSFS}"
 
-	find /sys -noleaf -type f -perm /444\
-		  -a -not -name "*trace_pipe*"\
-		  2>/dev/null | while IFS= read -r file_name; do
-	    echo " ${file_name}"
-	    if ! dd if="${file_name}" status=noxfer iflag=nonblock of="${WORKPATH}${file_name}" >/dev/null 2>&1; then
-		echo "${SCRIPTNAME}: Warning: failed to copy \"${file_name}\""
-	    fi
-	done
+	    find /sys -noleaf -type d 2>/dev/null | while IFS= read -r dir_name; do
+	        mkdir -p "${WORKPATH}${dir_name}"
+	    done
+
+	    find /sys -noleaf -type f -perm /444\
+		      -a -not -name "*trace_pipe*"\
+		      2>/dev/null | while IFS= read -r file_name; do
+		echo " ${file_name}"
+		if ! dd if="${file_name}" status=noxfer iflag=nonblock of="${WORKPATH}${file_name}" >/dev/null 2>&1; then
+		    echo "${SCRIPTNAME}: Warning: failed to copy \"${file_name}\""
+		fi
+	    done
+	fi
 
 	if test ${debugfs_mounted} -eq 1; then
 	    umount "${MOUNT_POINT_DEBUGFS}"