… for what would be 0% in many peoples mind. But what is even more important is hit ratio is not directly…rate so even taking data for single thread is not enough. So what should you look at ? The …things such as – how busy were drives with concurrent requests, how random were these reads/writes, how…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
…is basically what transaction is doing it can be “fetching rows”, “updating” and couple of other values. “Thread declared inside InnoDB 400″ means thread is…limit thread concurrency allowing only innodb_thread_concurrency threads to run inside Innodb kernel at the same time. If thread is not runniing…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
… it is also very interesting question what happens for blobs larger than 16K – is exact size allocated or also segment based allocation is used….1.x? Specifically: What’s the current status of innodb_thread_concurrency ? Is it suggested to set this value to a LARGE value…_SYSVAR_ULONG(thread_concurrency, srv_thread_concurrency, PLUGIN_VAR_RQCMDARG, “Helps in performance tuning in heavily concurrent environments. Sets the max\ imum number of threads allowed…
Post: MySQL 5.5 and MySQL 5.6 default variable values differences
February 21, 2013 By 8 Comments
… starvation of queued threads especially for IO bound workloads. Most users will not be affected though as innodb_thread_concurrency is 0 by default so this queuing feature is disabled. innodb_purge_threads is now 1 by default using dedicated background purge thread. Good… to 12M. I’m not sure what is the purpose of this change but it is unlikely to have any practical meaning for…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
… you what is now… concurrent_…thread_cache_sizeblogpercona.commanual thread_concurrencyblogpercona.commanual thread_handlingblogpercona.commanual thread_stackblogpercona.commanual Threads_cachedblogpercona.commanual Threads_connectedblogpercona.commanual Threads_createdblogpercona.commanual Threads…
Comment: Should MySQL update the default innodb_log_file_size?
November 24, 2011 By 37 Comments
…”, (ulong)srv_thread_concurrency); exit(1); } ==================== so log file size combined must be > 200kb * innodb thread concurrency.. The rationale behind this is mentioned just above… though the thread concurrency is a dynamic variable, that function is not called again. So, I wonder what will happen if I bump thread concurrency from say…
Post: Estimating Replication Capacity
July 20, 2010 By 4 Comments
… load” the inverse of replication capacity – this is basically what percentage of time the replication thread was busy replicating events vs staying idle… get replication load, which is same as “concurrency” figure (0.37x) The concurrency as reported by mk-query-digest is sum of query execution…
Post: MySQL QA Team Benchmarks for MySQL 5.1.30
December 13, 2008 By 12 Comments
… see what value is best for MySQL 5.1 and for MySQL 5.0 respectively ? Both versions do their best with innodb_thread_concurrency…, there is simply no data at all. It is also very interesting to see benchmark run with innodb_thread_concurrency=1000 – This is exactly the value which you should never use. The limit of 1000 threads inside the kernel is by…
Post: Side load may massively impact your MySQL Performance
November 13, 2011 By 7 Comments
… when concurrently. In the perfect world what we would like to see is performance is staying about the same when we run tests concurrently because… than 150 times when heavy mysqldump is running concurrently. mysqldump itself also slows down about 2x. What is going on here ? To understand it… of mysqldump is impacted too because we now have 2 threads competing for what is single hard drive on this test system. It is worth…
Post: Drilling down to the source of the problem
November 8, 2008 By 7 Comments
…, with innodb_thread_concurrency set to 8 Happily enough innodb_thread_concurrency is the variable which can be set online so it is easy to try a few different values and see what works… values and see what works best for you. As I mentioned in the start of this post changing innodb_thread_concurrency is happily online…
