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metze
Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Fri Jun 22 17:10:52 CEST 2012 on sn-devel-104
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This might not be needed, but it makes it more clear that
we won't use uninitialized memory, it the callback was not triggered.
metze
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Now dbwrap_fetch_int32 is used in smbd/locking/posix.c is used a
lot more often than before.
Signed-off-by: Stefan Metzmacher <metze@samba.org>
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Signed-off-by: Stefan Metzmacher <metze@samba.org>
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Signed-off-by: Stefan Metzmacher <metze@samba.org>
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It's not portable. While we could use ccan/err, it seems overkill since
we actually only use it in one test (I obviously cut & paste the #include).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Autobuild-User(master): Rusty Russell <rusty@rustcorp.com.au>
Autobuild-Date(master): Fri Jun 22 09:22:28 CEST 2012 on sn-devel-104
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(As suggested by Stefan Metzmacher, based on the change to ntdb.)
Since commit ec96ea690edbe3398d690b4a953d487ca1773f1c, we handle the case
where a process dies during a transaction commit. Unfortunately, TDB_NOSYNC
means this no longer works, as it disables the recovery area as well as the
actual msync/fsync. We should do everything except the syncs.
This also means we can do a complete test with $TDB_NO_FSYNC set; just
to get more complete coverage, we disable it explicitly for one test
(where we override the actual sync calls anyway).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Implemented for ntdb and tdb; falls back to 0 for others.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Useful for debug messages: particularly once we start switching between .tdb
and .ntdb files.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Implemented for ntdb and tdb; falls back to the blocking variant
for others.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Implemented for ntdb and tdb; falls back to the non-timeout variant
for others.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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This simply opens a tdb: it will eventually switch depending on the
extension.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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The flags returned were TDB-specific: this was only used for detecting
the endianness of obsolete databases (the conversion code was put in in
2003, with reference to Samba 2.3).
It's easier to remove it than to translate the NTDB flags to TDB flags,
and it's a really weird thing to ask for anyway.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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We're about to use them for dbwrap.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Similar to the util_tdb versions, but return the error code.
ntdb_add_int32_atomic seems a clearer name than tdb_change_int32_atomic.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Very similar to the tdb version.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Very similar to the util_tdb versions, but these return the error.
I've only implemented those functions actually used.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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There are various issues with NTDB_CLEAR_IF_FIRST which makes it
better if we don't have to use it, but much of the code does, so
we fake up support here.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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The first function is ntdb_new: this is preferred over ntdb_open, as
it makes the ntdb_context returned (and all NTDB_DATA returned from
ntdb_fetch) valid talloc pointers.
The API is very similar to tdb_wrap_open().
Note that we handle $TDB_NO_FSYNC here, since ntdb doesn't do that
hack (and it's great for speeding up testing!).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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This means we no longer have to unmap if we want to compare a record.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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In particular, this tests that we can store enough records to make the
database expand while we map the given record. We use a global lock for
this, but it could happen in theory with another process.
It also tests the that we can recurse inside ntdb_parse_record().
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Since we have a readlock, any write will grab a write lock: if it happens
to be on the same bucket, we'll fail.
For that reason, enforce read-only so every write operation fails
(even for NTDB_NOLOCK or NTDB_INTERNAL dbs), and document it!
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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NTDB_INTERNAL databases need to malloc and copy to keep old versions
around if we expand, in a similar way to the manner in which keep old
mmaps around.
Of course, it only works for read-only accesses, since the two copies
are not synced.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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This means keeping the old mmap around when we expand the database.
We could revert to read/write, except for platforms with incoherent
mmap (ie. OpenBSD), where we need to use mmap for all accesses.
Thus we keep a linked list of old maps, and unmap them when the last access
finally goes away.
This is required if we want ntdb_parse_record() callbacks to be able
to expand the database.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Since we can have multiple openers, we should leave the mmap in place
for the other openers to use. Enhance the test to check the bug (it
still works, because without mmap we fall back to read/write, but
performance would be terrible!).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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-ECUTNPASTE. This is not a usage error!
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Then we unset it inside the tdb test target itself. This means that
new code can't accidently forget it, and we can set it in the
'buildnice' script on sn-devel, for example.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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This reduces test time from 31 seconds to 6, on my laptop.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Autobuild-User(master): Jelmer Vernooij <jelmer@samba.org>
Autobuild-Date(master): Thu Jun 21 19:59:57 CEST 2012 on sn-devel-104
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Occasionally, the capability test inserts multiple used records and they
clash, but our primitive test layout engine doesn't handle hash clashes
and aborts.
Force a seed value which we know doesn't clash.
Reported-by: Andrew Bartlett <abartlet@samba.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Autobuild-User(master): Rusty Russell <rusty@rustcorp.com.au>
Autobuild-Date(master): Wed Jun 20 16:50:20 CEST 2012 on sn-devel-104
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This is copied from tdb; we build the utilities, but as nothing else
links against it, we shouldn't be adding anything to the normal samba
binary sizes.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Autobuild-User(master): Rusty Russell <rusty@rustcorp.com.au>
Autobuild-Date(master): Tue Jun 19 07:31:06 CEST 2012 on sn-devel-104
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Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Simple change, as we get rid of tdb_compat in favour of either ntdb directly
or dbwrap.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Simple change, as we get rid of tdb_compat in favour of tdb directly.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Update the design.lyx file with the latest status and the change in hashing.
Also, refresh and add examples to the TDB_porting.txt file.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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We access the key on lookup, then access the data in the caller. It
makes more sense to access both at once. We also put in a likely()
for the case where the hash is not chained.
Before:
Adding 1000 records: 3644-3724(3675) ns (129656 bytes)
Finding 1000 records: 1596-1696(1622) ns (129656 bytes)
Missing 1000 records: 1409-1525(1452) ns (129656 bytes)
Traversing 1000 records: 1636-1747(1668) ns (129656 bytes)
Deleting 1000 records: 3138-3223(3175) ns (129656 bytes)
Re-adding 1000 records: 3278-3414(3329) ns (129656 bytes)
Appending 1000 records: 5396-5529(5426) ns (253312 bytes)
Churning 1000 records: 9451-10095(9584) ns (253312 bytes)
smbtorture results (--entries=1000)
ntdb speed 183881-191112(188223) ops/sec
After:
Adding 1000 records: 3590-3701(3640) ns (129656 bytes)
Finding 1000 records: 1539-1605(1566) ns (129656 bytes)
Missing 1000 records: 1398-1440(1413) ns (129656 bytes)
Traversing 1000 records: 1629-2015(1710) ns (129656 bytes)
Deleting 1000 records: 3118-3236(3163) ns (129656 bytes)
Re-adding 1000 records: 3235-3355(3275) ns (129656 bytes)
Appending 1000 records: 5335-5444(5385) ns (253312 bytes)
Churning 1000 records: 9350-9955(9494) ns (253312 bytes)
smbtorture results (--entries=1000)
ntdb speed 180559-199981(195106) ops/sec
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Since our default hashsize is 8192 not 131, we look fat when we convert
near-empty TDBs.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Just like tdbtorture, having a hashsize of 2 stresses us much more!
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Since we've given up on expansion, let them frob the hashsize again.
We have attributes, so we should use them for optional stuff like
this.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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TDB2 started with a top-level hash of 1024 entries, divided into 128
groups of 8 buckets. When a bucket filled, the 8 bucket group
expanded into pointers into 8 new 64-entry hash tables. When these
filled, they expanded in turn, etc.
It's a nice idea to automatically expand the hash tables, but it
doesn't pay off. Remove it for NTDB.
1) It only beats TDB performance when the database is huge and the
TDB hashsize is small. We are about 20% slower on medium-size
databases (1000 to 10000 records), worse on really small ones.
2) Since we're 64 bits, our hash tables are already twice as expensive
as TDB.
3) Since our hash function is good, it means that all groups tend to
fill at the same time, meaning the hash enlarges by a factor of 128
all at once, leading to a very large database at that point.
4) Our efficiency would improve if we enlarged the top level, but
that makes our minimum db size even worse: it's already over 8k,
and jumps to 1M after about 1000 entries!
5) Making the sub group size larger gives a shallower tree, which
performs better, but makes the "hash explosion" problem worse.
6) The code is complicated, having to handle delete and reshuffling
groups of hash buckets, and expansion of buckets.
7) We have to handle the case where all the records somehow end up with
the same hash value, which requires special code to chain records for
that case.
On the other hand, it would be nice if we didn't degrade as badly as
TDB does when the hash chains get long.
This patch removes the hash-growing code, but instead of chaining like
TDB does when a bucket fills, we point the bucket to an array of
record pointers. Since each on-disk NTDB pointer contains some hash
bits from the record (we steal the upper 8 bits of the offset), 99.5%
of the time we don't need to load the record to determine if it
matches. This makes an array of offsets much more cache-friendly than
a linked list.
Here are the times (in ns) for tdb_store of N records, tdb_store of N
records the second time, and a fetch of all N records. I've also
included the final database size and the smbtorture local.[n]tdb_speed
results.
Benchmark details:
1) Compiled with -O2.
2) assert() was disabled in TDB2 and NTDB.
3) The "optimize fetch" patch was applied to NTDB.
10 runs, using tmpfs (otherwise massive swapping as db hits ~30M,
despite plenty of RAM).
Insert Re-ins Fetch Size dbspeed
(nsec) (nsec) (nsec) (Kb) (ops/sec)
TDB (10000 hashsize):
100 records: 3882 3320 1609 53 203204
1000 records: 3651 3281 1571 115 218021
10000 records: 3404 3326 1595 880 202874
100000 records: 4317 3825 2097 8262 126811
1000000 records: 11568 11578 9320 77005 25046
TDB2 (1024 hashsize, expandable):
100 records: 3867 3329 1699 17 187100
1000 records: 4040 3249 1639 154 186255
10000 records: 4143 3300 1695 1226 185110
100000 records: 4481 3425 1800 17848 163483
1000000 records: 4055 3534 1878 106386 160774
NTDB (8192 hashsize)
100 records: 4259 3376 1692 82 190852
1000 records: 3640 3275 1566 130 195106
10000 records: 4337 3438 1614 773 188362
100000 records: 4750 5165 1746 9001 169197
1000000 records: 4897 5180 2341 83838 121901
Analysis:
1) TDB wins on small databases, beating TDB2 by ~15%, NTDB by ~10%.
2) TDB starts to lose when hash chains get 10 long (fetch 10% slower
than TDB2/NTDB).
3) TDB does horribly when hash chains get 100 long (fetch 4x slower
than NTDB, 5x slower than TDB2, insert about 2-3x slower).
4) TDB2 databases are 40% larger than TDB1. NTDB is about 15% larger
than TDB1
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We also split off the NTDB_CONVERT case (where the ntdb is of a
different endian) into its own io function.
NTDB speed:
Adding 10000 records: 3894-9951(8553) ns (815528 bytes)
Finding 10000 records: 1644-4294(3580) ns (815528 bytes)
Missing 10000 records: 1497-4018(3303) ns (815528 bytes)
Traversing 10000 records: 1585-4225(3505) ns (815528 bytes)
Deleting 10000 records: 3088-8154(6927) ns (815528 bytes)
Re-adding 10000 records: 3192-8308(7089) ns (815528 bytes)
Appending 10000 records: 5187-13307(11365) ns (1274312 bytes)
Churning 10000 records: 6772-17567(15078) ns (1274312 bytes)
NTDB speed in transaction:
Adding 10000 records: 1602-2404(2214) ns (815528 bytes)
Finding 10000 records: 456-871(778) ns (815528 bytes)
Missing 10000 records: 393-522(503) ns (815528 bytes)
Traversing 10000 records: 729-1015(945) ns (815528 bytes)
Deleting 10000 records: 1065-1476(1374) ns (815528 bytes)
Re-adding 10000 records: 1397-1930(1819) ns (815528 bytes)
Appending 10000 records: 2927-3351(3184) ns (1274312 bytes)
Churning 10000 records: 3921-4697(4378) ns (1274312 bytes)
smbtorture results:
ntdb speed 86581-191518(175666) ops/sec
Applying patch..increase-top-level.patch
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The simple "is it in range" check can be inline; complex cases can be
handed through to the normal or transaction handler.
NTDB speed:
Adding 10000 records: 4111-9983(9149) ns (815528 bytes)
Finding 10000 records: 1667-4464(3810) ns (815528 bytes)
Missing 10000 records: 1511-3992(3546) ns (815528 bytes)
Traversing 10000 records: 1698-4254(3724) ns (815528 bytes)
Deleting 10000 records: 3608-7998(7358) ns (815528 bytes)
Re-adding 10000 records: 3259-8504(7805) ns (815528 bytes)
Appending 10000 records: 5393-13579(12356) ns (1274312 bytes)
Churning 10000 records: 6966-17813(16136) ns (1274312 bytes)
NTDB speed in transaction:
Adding 10000 records: 916-2230(2004) ns (815528 bytes)
Finding 10000 records: 330-866(770) ns (815528 bytes)
Missing 10000 records: 196-520(471) ns (815528 bytes)
Traversing 10000 records: 356-879(800) ns (815528 bytes)
Deleting 10000 records: 505-1267(1108) ns (815528 bytes)
Re-adding 10000 records: 658-1681(1477) ns (815528 bytes)
Appending 10000 records: 1088-2827(2498) ns (1274312 bytes)
Churning 10000 records: 1636-4267(3785) ns (1274312 bytes)
smbtorture results:
ntdb speed 85588-189430(157110) ops/sec
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This is designed to allow us to make ntdb_context (and NTDB_DATA returned
from ntdb_fetch) a talloc pointer. But it can also be used for any other
alternate allocator.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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NTDB_NOSYNC now just prevents the fsync/msync calls, which speeds
testing while still providing full coverage. It also provides safety
against processes dying during transaction commit (though obviously,
not against the machine dying).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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TDB allows this for internal databases, but it's a bad idea, since the
name is useful for logging.
They're a hassle to deal with, and we'd just end up putting "unnamed"
in there, so let the user deal with it. If they don't, they get an
informative core dump.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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The performance numbers for transaction pagesize are indeterminate:
larger pagesizes means a smaller transaction array, and a better
chance of having a contiguous record (more efficient for
ntdb_parse_record and some internal operations inside a transaction).
On the other hand, large pagesize means more I/O even if we change a
few bytes.
But it also controls the multiple by which we will enlarge the file,
and hence the minimum db size. It's 4k for tdb1, but 16k seems
reasonable in these modern times.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Now our database is always a multiple of NTDB_PGSIZE, we can remove the
special handling for the last block.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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