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| author | Rusty Russell <rusty@rustcorp.com.au> | 2010-08-14 02:13:26 +0930 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2010-08-14 02:31:22 +0930 |
| commit | 11ab43084b10cf53b530cdc3a6036c898b79ca38 (patch) | |
| tree | 04549a9c16f5e68349aded2f8ead56571df01312 /lib/tdb/configure.ac | |
| parent | f00b61c7d4611802c66495824c97af6cad69704e (diff) | |
| download | samba-11ab43084b10cf53b530cdc3a6036c898b79ca38.tar.gz samba-11ab43084b10cf53b530cdc3a6036c898b79ca38.tar.bz2 samba-11ab43084b10cf53b530cdc3a6036c898b79ca38.zip | |
tdb: workaround starvation problem in locking entire database.
We saw tdb_lockall() take 71 seconds under heavy load; this is because Linux
(at least) doesn't prevent new small locks being obtained while we're waiting
for a big log.
The workaround is to do divide and conquer using non-blocking chainlocks: if
we get down to a single chain we block. Using a simple test program where
children did "hold lock for 100ms, sleep for 1 second" the time to do
tdb_lockall() dropped signifiantly. There are ln(hashsize) locks taken in
the contended case, but that's slow anyway.
More analysis is given in my blog at http://rusty.ozlabs.org/?p=120
This may also help transactions, though in that case it's the initial
read lock which uses this gradual locking routine; the update-to-write-lock
code is separate and still tries to update in one go.
Even though ABI doesn't change, minor version bumped so behavior change
can be easily detected.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'lib/tdb/configure.ac')
| -rw-r--r-- | lib/tdb/configure.ac | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/tdb/configure.ac b/lib/tdb/configure.ac index 4e36779df2..2843d98ec8 100644 --- a/lib/tdb/configure.ac +++ b/lib/tdb/configure.ac @@ -2,7 +2,7 @@ AC_PREREQ(2.50) AC_DEFUN([SMB_MODULE_DEFAULT], [echo -n ""]) AC_DEFUN([SMB_LIBRARY_ENABLE], [echo -n ""]) AC_DEFUN([SMB_ENABLE], [echo -n ""]) -AC_INIT(tdb, 1.2.2) +AC_INIT(tdb, 1.2.3) AC_CONFIG_SRCDIR([common/tdb.c]) AC_CONFIG_HEADER(include/config.h) AC_LIBREPLACE_ALL_CHECKS |