Re: Delta-syncrepl and latency

["Sam Tran" <stlist@gmail.com>]

On 5/9/07, Quanah Gibson-Mount <quanah@zimbra.com> wrote:
> --On May 9, 2007 12:46:18 PM -0400 Sam Tran <stlist@gmail.com> wrote:
>
> > On 5/8/07, Quanah Gibson-Mount <quanah@zimbra.com> wrote:
> > [snip]
> >>
> >> How have you tuned DB_CONFIG for the accesslog backend?
> >>
> >> --Quanah
> >>
> >
> > Here is my DB_CONFIG for the accesslog backend:
> >
> > set_cachesize   0       52428800        0
> > set_lg_regionmax        1048576
> > set_lg_max              10485760
> > set_lg_bsize            2097152
> > set_lg_dir              /var/log/openldap_bdb/accesslog
> > set_tmp_dir             /tmp
>
> Have you looked at the output of db_stat -m to see how things are behaving?

I ran 1,000 sequential writes on the provider. Then run the command
you specified. Here is the output:

[root@info-ldap-004 accesslog]# /usr/local/BerkeleyDB.4.5/bin/db_stat -m
62MB 513KB 900B Total cache size
1       Number of caches
62MB 520KB      Pool individual cache size
0       Maximum memory-mapped file size
0       Maximum open file descriptors
0       Maximum sequential buffer writes
0       Sleep after writing maximum sequential buffers
0       Requested pages mapped into the process' address space
904312  Requested pages found in the cache (99%)
16      Requested pages not found in the cache
1483    Pages created in the cache
16      Pages read into the cache
38      Pages written from the cache to the backing file
0       Clean pages forced from the cache
0       Dirty pages forced from the cache
0       Dirty pages written by trickle-sync thread
1499    Current total page count
4       Current clean page count
1495    Current dirty page count
8191    Number of hash buckets used for page location
905825  Total number of times hash chains searched for a page
2       The longest hash chain searched for a page
921930  Total number of hash chain entries checked for page
1       The number of hash bucket locks that required waiting (0%)
1       The maximum number of times any hash bucket lock was waited for (0%)
0       The number of region locks that required waiting (0%)
0       The number of buffers frozen
0       The number of buffers thawed
0       The number of frozen buffers freed
1539    The number of page allocations
0       The number of hash buckets examined during allocations
0       The maximum number of hash buckets examined for an allocation
0       The number of pages examined during allocations
0       The max number of pages examined for an allocation
0       Threads waited on page I/O
Pool File: reqStart.bdb
4096    Page size
0       Requested pages mapped into the process' address space
51707   Requested pages found in the cache (99%)
2       Requested pages not found in the cache
37      Pages created in the cache
2       Pages read into the cache
3       Pages written from the cache to the backing file
Pool File: entryUUID.bdb
4096    Page size
0       Requested pages mapped into the process' address space
43212   Requested pages found in the cache (99%)
2       Requested pages not found in the cache
69      Pages created in the cache
2       Pages read into the cache
4       Pages written from the cache to the backing file
Pool File: objectClass.bdb
4096    Page size
0       Requested pages mapped into the process' address space
382439  Requested pages found in the cache (99%)
2       Requested pages not found in the cache
114     Pages created in the cache
2       Pages read into the cache
4       Pages written from the cache to the backing file
Pool File: reqEnd.bdb
4096    Page size
0       Requested pages mapped into the process' address space
51688   Requested pages found in the cache (99%)
2       Requested pages not found in the cache
37      Pages created in the cache
2       Pages read into the cache
3       Pages written from the cache to the backing file
Pool File: id2entry.bdb
16384   Page size
0       Requested pages mapped into the process' address space
112069  Requested pages found in the cache (99%)
2       Requested pages not found in the cache
668     Pages created in the cache
2       Pages read into the cache
9       Pages written from the cache to the backing file
Pool File: reqResult.bdb
4096    Page size
0       Requested pages mapped into the process' address space
84952   Requested pages found in the cache (99%)
2       Requested pages not found in the cache
28      Pages created in the cache
2       Pages read into the cache
3       Pages written from the cache to the backing file
Pool File: entryCSN.bdb
4096    Page size
0       Requested pages mapped into the process' address space
52002   Requested pages found in the cache (99%)
2       Requested pages not found in the cache
37      Pages created in the cache
2       Pages read into the cache
4       Pages written from the cache to the backing file
Pool File: dn2id.bdb
4096    Page size
0       Requested pages mapped into the process' address space
126243  Requested pages found in the cache (99%)
2       Requested pages not found in the cache
493     Pages created in the cache
2       Pages read into the cache
8       Pages written from the cache to the backing file

According to the output most of the data is in cache.
It took about 5 minutes for the consumer to get the updates.
I still don't know why.

Sam