If it`s INTEL Quad-Core processors, cores are not independent. Includes 2 core
pairs, each pair using common level 2 cache - good for Windows desktop
applications only, I think.
It`s a common view only, not detailed analyse.
Moreover, Em64T Intel tehnology is a strange one, if more then 4 GB RAM
installed.
Oracle (current owner of MySQL AB) suggests AMD64 processors.
Forgive me poor English and possible oftopic, please...
Date: Wed, 20 Aug 2008 09:46:55 -0500From: [EMAIL PROTECTED]: [EMAIL
PROTECTED]: Re: [Dbmail] Query to show mailbox folders running slow
It turns out the problem is related to a well documented issue with mulit-core
processors and MySQL running INNODB. We had to drop the thread concurrency to
1 in MySQL to get our load tests to finish properly. The low thread
concurrency unfortunately causes issues when it comes to syncing off our
existing system onto the new dbmail system; our times went from 8 hrs to over
15 hrs using IMAPSYNC. Through some trial and error, we determined that for
optimal syncing, thread concurrency needs to be set at 5 and for standard use
thread concurrency needs to be set to 1.Here are some links documenting the
Multi-Core Innodb MySQL
issue.http://www.bigdbahead.com/?p=59http://mysqlguy.net/blog/2008/07/16/innodb-multi-core-performancehttp://www.anandtech.com/IT/showdoc.aspx?i=2772&p=9Unfortunately
we didn't know this when we bought our 4XQuad-Core Server (16 cores).Thanks,Rob
On Wed, Aug 20, 2008 at 7:38 AM, Paul J Stevens <[EMAIL PROTECTED]> wrote:
My guess is this is a table-locking issue, something you can easily determine
bylooking at mytop or 'mysqladmin processlist' during the slowdown. I can
notcomment on your parameters since I don't know what kind of resources the
mysqlserver has.
David Suehring wrote:> Hey everybody,>> We are running into a few issues when
running some load tests on dbmail.> As we are running the test, I've noticed
that the following query goes> from running nearly instantly, to taking
anywhere from 10-20 seconds:>> SELECT distinct(mbx.name <http://mbx.name>),
mbx.mailbox_idnr,
> mbx.owner_idnr FROM dbmail_mailboxes mbx LEFT JOIN dbmail_acl acl ON>
> mbx.mailbox_idnr = acl.mailbox_id> LEFT JOIN dbmail_users usr ON acl.user_id
> = usr.user_idnr WHERE> ((mbx.owner_idnr = 2676) OR (acl.user_id = 2676 AND
> acl.lookup_flag => 1) OR (usr.userid = 'anyone' AND acl.lookup_flag = 1))>>
> As far as our setup goes, we are using dbmail 2.2.10 with MySQL 5.0.26.>
> <http://5.0.26.> Our dbmail_mailboxes table currently has about 47000
> rows, dbmail_users has about 4000 rows, and dbmail_acl has 0 rows. The> load
> test we are doing uses a web interface to connect to dbmail, read a> message,
> send a message, and repeat. When we simulate 10 users doing> this, we do not
> see any performance issues. Once we increase to 20> users, the query above
> begins to take longer and longer, reaching nearly> 20 seconds in some
> situations. I realize that this is most likely a> snowball effect, where once
> it hits a snag, the queries just pile up and> become slower as a result. Does
> anyone have any configuration tips or> thoughts on how to help speed this up
> and prevent the slowdown?>> Here is our my.cnf configuration:>> # The MySQL
> server> [mysqld]> port = 3306> socket
> = /var/lib/mysql/mysql.sock> max_connections =
> 200> skip-locking> key_buffer = 16M> max_allowed_packet
> = 8M> table_cache = 1024> sort_buffer_size
> = 2M> read_buffer_size = 2M> read_rnd_buffer_size
> = 8M> myisam_sort_buffer_size = 8M> thread_cache_size
> = 16> query_cache_size = 128M> query_cache_limit
> = 2M> long_query_time = 1> tmpdir = /tmp> datadir =
> /var/lib/mysql> thread_concurrency = 16>> # InnoDB settings>
> innodb_file_per_table> innodb_data_home_dir = /var/lib/mysql/>
> innodb_data_file_path = ibdata1:10M:autoextend>
> innodb_log_group_home_dir = /var/lib/mysql/> innodb_log_arch_dir
> = /var/lib/mysql/> innodb_log_files_in_group = 2>
> innodb_buffer_pool_size = 24576M> innodb_additional_mem_pool_size =
> 20M> innodb_log_file_size = 512M> innodb_log_buffer_size
> = 16M> innodb_flush_log_at_trx_commit = 1> innodb_lock_wait_timeout =
> 50> innodb_thread_concurrency = 8>> [mysqldump]> quick>
> max_allowed_packet = 16M> [mysql]> no-auto-rehash> # Remove the next comment
> character if you are not familiar with SQL> #safe-updates> [isamchk]>
> key_buffer = 256M> sort_buffer_size = 256M> read_buffer
> = 2M> write_buffer = 2M> [myisamchk]> key_buffer
> = 256M> sort_buffer_size = 256M> read_buffer = 2M>
> write_buffer = 2M> [mysqlhotcopy]> interactive-timeout> If there
> is any other information that would be helpful, please let me> know.>> Thanks
> for any help!>> -David>>>
> ------------------------------------------------------------------------>>
> _______________________________________________> DBmail mailing list>
> [email protected]> https://mailman.fastxs.nl/mailman/listinfo/dbmail--
> ________________________________________________________________ Paul Stevens
> paul at nfg.nl NET FACILITIES GROUP
> GPG/PGP: 1024D/11F8CD31 The
> Netherlands________________________________http://www.nfg.nl_______________________________________________DBmail
> mailing [EMAIL PROTECTED]://mailman.fastxs.nl/mailman/listinfo/dbmail
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