… ext4 is a standard de facto filesystem for many modern Linux system, I am getting a lot of question if this… Percona Server 5.1 and 5.5), InnoDB uses “asynchronous” IO in Linux. Let’s test “async” mode in sysbench, and now…. 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… was not really significant. This article also points out benchmarking IO schedulers you should look at more numbers than aggregate bandwidth – you…
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 have not seen anything production ready. So what I would like to see ? Each IO request… want to happen in background when there are enough resources. IO Scheduler should execute these only if there is bandwidth available so…
Post: XtraDB benchmarks - 1.5X gain in IO-bound load
December 18, 2008 By 30 Comments
… to run MySQL on. What is important I used Noop IO scheduler, instead of default CFQ. Disclaimer: Please note you may not… 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: Linux schedulers in tpcc like benchmark
January 30, 2009 By 19 Comments
I mentioned earlier that IO scheduler CFQ coming by default in RedHat / CentOS 5.x may … reported that just changing cfq to noop solved their InnoDB IO problems. I ran tpcc scripts against XtraDB on our Dell…_flush_method = O_DIRECT innodb_write_io_threads=4 innodb_read_io_threads=4 innodb_io_capacity=800 innodb_adaptive_checkpoint=1 max…
Comment: Linux schedulers in tpcc like benchmark
January 30, 2009 By 19 Comments
I have detailed why this happens at http://dammit.lt/2008/02/05/linux-io-schedulers/ – though it all started simply when we compared how I/O behaves on identical machines ( http://dammit.lt/2007/12/13/io-scheduler-deadline-cfq/ )
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… nobarrier,noatime,nodiratime Setting the IO scheduler This is a commonly missed step related to getting the IO setup properly. The best choices…
Post: Performance impact of complex queries
January 17, 2007 By 11 Comments
… more than few milliseconds you would expect disk IO to take. Scheduling Issues OS Disk IO schedules may also “help” in this case. Number… IO requests in random locations other threads are willing to take. Especially some older disk schedulers could be poor. I remember in Linux… for directory with couple of files. In recent Linux Kernels deadline or cfq IO schedulers should be better with this. So what can…
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 # … compare performance with different IO alignment, not different MySQL …
Comment: Linux schedulers in tpcc like benchmark
January 31, 2009 By 19 Comments
benpi, Did Linux get per request priorities finally ? I worked with an University some time ago to see how IO priorities can… queue sizes without starving log writes etc. Now about disk IO scheduling and cache. Really it is a bit different though connected… dirty pages there is indeed a better chance to optimize IO.
