…-plugin and later MySQL 5.5 (or equally Percona Server 5.1 and 5.5), InnoDB uses “asynchronous” IO in Linux. Let’s… question I was asked, namely: “If MySQL 5.5 uses async IO, is innodb_write_io_threads still important?”, and it seems it…. I would still use value 2 or 4, to avoid scheduling overhead from single thread, but it does not seem critical…
Post: Linux IO Schedulers and MySQL
January 30, 2007 By 7 Comments
… about Linux IO Schedulers today which is quite interesting. It goes in details about schedulers and explains in which of workloads which of schedulers is… the docs it is mentioned it uses “per process” scheduling while MySQL is single process but single thread – does each thread gets…
Post: XtraDB benchmarks - 1.5X gain in IO-bound load
December 18, 2008 By 30 Comments
… quite typical server we recommend to run MySQL on. What is important I used Noop IO scheduler, instead of default CFQ. Disclaimer: Please… better. Finally let me show you why I took NOOP IO scheduler instead of CFQ, there are result for XtraDB with both… remember as Linux kernels 2.6.18+ (which are used on CentOS / RedHat 5.2) are coming with CFQ scheduler as default…
Post: Operation Systems do not provide good IO interface for Database Servers
May 11, 2006 By 2 Comments
… accounted for while executing IO request. Last time I checked there was IO scheduler with these functions in works for Linux Kernel but I… want to happen in background when there are enough resources. IO Scheduler should execute these only if there is bandwidth available so…” projects at DIKU We tested some protototype patches for Linux kernel and MySQL but we did not get anything ready for production…
Post: Linux schedulers in tpcc like benchmark
January 30, 2009 By 19 Comments
… mentioned earlier that IO scheduler CFQ coming by default in RedHat / CentOS 5.x may be not so good for MySQL. And yesterday one customer reported that just changing cfq to noop solved their InnoDB IO problems. I ran…_flush_method = O_DIRECT innodb_write_io_threads=4 innodb_read_io_threads=4 innodb_io_capacity=800 innodb_adaptive_checkpoint=1 max…
Post: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 11 Comments
…# Aspersa System Summary Report ############################## Platform | Linux Release | Ubuntu 10.04.2 LTS… {OUT OF SPEC} Other … # Disk Schedulers And Queue Size ############################# sda | [deadline] 128 #…IO alignment, not different MySQL configurations, I didn’t try out different MySQL…
Post: Setting up XFS on Hardware RAID -- the simple edition
December 16, 2011 By 9 Comments
… boundary. /dev/sda2 * 7813120 27344895 9765888 83 Linux /dev/sda3 27344896 856422399 414538752 83 Linux Several months ago my colleague Aurimas posted…: /var/lib/mysql xfs nobarrier,noatime,nodiratime Setting the IO scheduler This is a commonly missed step related to getting the IO setup properly…
Post: Performance impact of complex queries
January 17, 2007 By 11 Comments
… your normal working set from OS cache. Operation Systems and MySQL Itself employs various strategies to attempt to minimize such effect… more than few milliseconds you would expect disk IO to take. Scheduling Issues OS Disk IO schedules may also “help” in this case. Number… for directory with couple of files. In recent Linux Kernels deadline or cfq IO schedulers should be better with this. So what can…
Post: The new cool MySQL patch has landed! Check your queries performance!
October 31, 2007 By 16 Comments
…: 56 Rows_examined: 1113 LOGGING OF THE REPLICATED STATEMENTS Normally MySQL will not write into slow log any queries executed by…_pages_distinct: 20 InnoDB_IO_r_ops is the counter for the number of page read operations scheduled. The acutal number of… any important system! The patch is available for MySQL Community 5.0.45 on Linux. May not work on other systems. Maciek…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 17 Comments
…. I thought Innodb will make sure to schedule synchronous wait in front if read-ahead IO has not been started already. The…) to swap out MySQL. There are two solutions here. Memlock and O_DIRECT. Memlock is apparently unstable on Linux. O_DIRECT is…: memlock already works – it is global MySQL Server option, though it may have problems on Linux if you lock very large portion…
