Add dbuf hash and dbuf cache kstats

Introduce kstats about the dbuf hash and dbuf cache
to make it easier to inspect state. This should help
with debugging and understanding of these portions
of the codebase.

Correct format of dbuf kstat file.

Introduce a dbc column to dbufs kstat to indicate if
a dbuf is in the dbuf cache.

Introduce field filtering in the dbufstat python script.

Introduce a no header option to the dbufstat python script.

Introduce a test case to test basic mru->mfu list movement
in the ARC.

Reviewed-by: Tony Hutter <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Giuseppe Di Natale <[email protected]>
Closes #6906 

1 files changed, 77 insertions, 17 deletions

diff --git a/cmd/dbufstat/dbufstat.py b/cmd/dbufstat/dbufstat.py
index 1e0f4c31e..517477b21 100755
--- a/cmd/dbufstat/dbufstat.py
+++ b/cmd/dbufstat/dbufstat.py
@@ -31,10 +31,11 @@
 import sys
 import getopt
 import errno
+import re
 
 bhdr = ["pool", "objset", "object", "level", "blkid", "offset", "dbsize"]
 bxhdr = ["pool", "objset", "object", "level", "blkid", "offset", "dbsize",
-         "meta", "state", "dbholds", "list", "atype", "flags",
+         "meta", "state", "dbholds", "dbc", "list", "atype", "flags",
          "count", "asize", "access", "mru", "gmru", "mfu", "gmfu", "l2",
          "l2_dattr", "l2_asize", "l2_comp", "aholds", "dtype", "btype",
          "data_bs", "meta_bs", "bsize", "lvls", "dholds", "blocks", "dsize"]
@@ -45,7 +46,7 @@ dxhdr = ["pool", "objset", "object", "dtype", "btype", "data_bs", "meta_bs",
          "bsize", "lvls", "dholds", "blocks", "dsize", "cached", "direct",
          "indirect", "bonus", "spill"]
 dincompat = ["level", "blkid", "offset", "dbsize", "meta", "state", "dbholds",
-             "list", "atype", "flags", "count", "asize", "access",
+             "dbc", "list", "atype", "flags", "count", "asize", "access",
              "mru", "gmru", "mfu", "gmfu", "l2", "l2_dattr", "l2_asize",
              "l2_comp", "aholds"]
 
@@ -53,7 +54,7 @@ thdr = ["pool", "objset", "dtype", "cached"]
 txhdr = ["pool", "objset", "dtype", "cached", "direct", "indirect",
          "bonus", "spill"]
 tincompat = ["object", "level", "blkid", "offset", "dbsize", "meta", "state",
-             "dbholds", "list", "atype", "flags", "count", "asize",
+             "dbc", "dbholds", "list", "atype", "flags", "count", "asize",
              "access", "mru", "gmru", "mfu", "gmfu", "l2", "l2_dattr",
              "l2_asize", "l2_comp", "aholds", "btype", "data_bs", "meta_bs",
              "bsize", "lvls", "dholds", "blocks", "dsize"]
@@ -70,9 +71,10 @@ cols = {
     "meta":       [4,    -1, "is this buffer metadata?"],
     "state":      [5,    -1, "state of buffer (read, cached, etc)"],
     "dbholds":    [7,  1000, "number of holds on buffer"],
+    "dbc":        [3,    -1, "in dbuf cache"],
     "list":       [4,    -1, "which ARC list contains this buffer"],
     "atype":      [7,    -1, "ARC header type (data or metadata)"],
-    "flags":      [8,    -1, "ARC read flags"],
+    "flags":      [9,    -1, "ARC read flags"],
     "count":      [5,    -1, "ARC data count"],
     "asize":      [7,  1024, "size of this ARC buffer"],
     "access":     [10,   -1, "time this ARC buffer was last accessed"],
@@ -104,8 +106,8 @@ cols = {
 hdr = None
 xhdr = None
 sep = "  "  # Default separator is 2 spaces
-cmd = ("Usage: dbufstat.py [-bdhrtvx] [-i file] [-f fields] [-o file] "
-       "[-s string]\n")
+cmd = ("Usage: dbufstat.py [-bdhnrtvx] [-i file] [-f fields] [-o file] "
+       "[-s string] [-F filter]\n")
 raw = 0
 
 
@@ -151,6 +153,7 @@ def usage():
     sys.stderr.write("\t -b : Print table of information for each dbuf\n")
     sys.stderr.write("\t -d : Print table of information for each dnode\n")
     sys.stderr.write("\t -h : Print this help message\n")
+    sys.stderr.write("\t -n : Exclude header from output\n")
     sys.stderr.write("\t -r : Print raw values\n")
     sys.stderr.write("\t -t : Print table of information for each dnode type"
                      "\n")
@@ -162,11 +165,13 @@ def usage():
     sys.stderr.write("\t -o : Redirect output to the specified file\n")
     sys.stderr.write("\t -s : Override default field separator with custom "
                      "character or string\n")
+    sys.stderr.write("\t -F : Filter output by value or regex\n")
     sys.stderr.write("\nExamples:\n")
     sys.stderr.write("\tdbufstat.py -d -o /tmp/d.log\n")
     sys.stderr.write("\tdbufstat.py -t -s \",\" -o /tmp/t.log\n")
     sys.stderr.write("\tdbufstat.py -v\n")
     sys.stderr.write("\tdbufstat.py -d -f pool,object,objset,dsize,cached\n")
+    sys.stderr.write("\tdbufstat.py -bx -F dbc=1,objset=54,pool=testpool\n")
     sys.stderr.write("\n")
 
     sys.exit(1)
@@ -409,12 +414,32 @@ def update_dict(d, k, line, labels):
     return d
 
 
-def print_dict(d):
-    print_header()
+def skip_line(vals, filters):
+    '''
+    Determines if a line should be skipped during printing
+    based on a set of filters
+    '''
+    if len(filters) == 0:
+        return False
+
+    for key in vals:
+        if key in filters:
+            val = prettynum(cols[key][0], cols[key][1], vals[key]).strip()
+            # we want a full match here
+            if re.match("(?:" + filters[key] + r")\Z", val) is None:
+                return True
+
+    return False
+
+
+def print_dict(d, filters, noheader):
+    if not noheader:
+        print_header()
     for pool in list(d.keys()):
         for objset in list(d[pool].keys()):
             for v in list(d[pool][objset].values()):
-                print_values(v)
+                if not skip_line(v, filters):
+                    print_values(v)
 
 
 def dnodes_build_dict(filehandle):
@@ -455,7 +480,7 @@ def types_build_dict(filehandle):
     return types
 
 
-def buffers_print_all(filehandle):
+def buffers_print_all(filehandle, filters, noheader):
     labels = dict()
 
     # First 3 lines are header information, skip the first two
@@ -466,11 +491,14 @@ def buffers_print_all(filehandle):
     for i, v in enumerate(next(filehandle).split()):
         labels[v] = i
 
-    print_header()
+    if not noheader:
+        print_header()
 
     # The rest of the file is buffer information
     for line in filehandle:
-        print_values(parse_line(line.split(), labels))
+        vals = parse_line(line.split(), labels)
+        if not skip_line(vals, filters):
+            print_values(vals)
 
 
 def main():
@@ -487,11 +515,13 @@ def main():
     tflag = False
     vflag = False
     xflag = False
+    nflag = False
+    filters = dict()
 
     try:
         opts, args = getopt.getopt(
             sys.argv[1:],
-            "bdf:hi:o:rs:tvx",
+            "bdf:hi:o:rs:tvxF:n",
             [
                 "buffers",
                 "dnodes",
@@ -502,7 +532,8 @@ def main():
                 "seperator",
                 "types",
                 "verbose",
-                "extended"
+                "extended",
+                "filter"
             ]
         )
     except getopt.error:
@@ -532,6 +563,35 @@ def main():
             vflag = True
         if opt in ('-x', '--extended'):
             xflag = True
+        if opt in ('-n', '--noheader'):
+            nflag = True
+        if opt in ('-F', '--filter'):
+            fils = [x.strip() for x in arg.split(",")]
+
+            for fil in fils:
+                f = [x.strip() for x in fil.split("=")]
+
+                if len(f) != 2:
+                    sys.stderr.write("Invalid filter '%s'.\n" % fil)
+                    sys.exit(1)
+
+                if f[0] not in cols:
+                    sys.stderr.write("Invalid field '%s' in filter.\n" % f[0])
+                    sys.exit(1)
+
+                if f[0] in filters:
+                    sys.stderr.write("Field '%s' specified multiple times in "
+                                     "filter.\n" % f[0])
+                    sys.exit(1)
+
+                try:
+                    re.compile("(?:" + f[1] + r")\Z")
+                except re.error:
+                    sys.stderr.write("Invalid regex for field '%s' in "
+                                     "filter.\n" % f[0])
+                    sys.exit(1)
+
+                filters[f[0]] = f[1]
 
     if hflag or (xflag and desired_cols):
         usage()
@@ -594,13 +654,13 @@ def main():
             sys.exit(1)
 
     if bflag:
-        buffers_print_all(sys.stdin)
+        buffers_print_all(sys.stdin, filters, nflag)
 
     if dflag:
-        print_dict(dnodes_build_dict(sys.stdin))
+        print_dict(dnodes_build_dict(sys.stdin), filters, nflag)
 
     if tflag:
-        print_dict(types_build_dict(sys.stdin))
+        print_dict(types_build_dict(sys.stdin), filters, nflag)
 
 
 if __name__ == '__main__':