… ext4 is a standard de facto filesystem for many modern Linux system, I am getting a lot of question if this… 5.1 and 5.5), InnoDB uses “asynchronous” IO in Linux. Let’s test “async” mode in sysbench, and now we…. I would still use value 2 or 4, to avoid scheduling overhead from single thread, but it does not seem critical…
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 …
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… not really significant. This article also points out benchmarking IO schedulers you should look at more numbers than aggregate bandwidth – you…
Post: Fast storage: 8 SSD Intel X-25M 80GB benchmarks
January 18, 2010 By 15 Comments
… connected in software RAIDs: RAID0 and RAID10 with different OS schedules over each device. I should highlight I do not see… point for research, I think there some serialization in Linux software raid or Linux scheduler or on Adaptec hardware level. 2. Cards connected… different options: connect them in software or hardware raids, what scheduler to pick, etc. I suggest to run sysbench fileio or…
Comment: FlashCache: tpcc workload
May 26, 2010 By 18 Comments
…. See for example http://www.mysqlperformanceblog.com/2009/01/30/linux-schedulers-in-tpcc-like-benchmark/ Also we have bunch of customers… just by one command echo deadline > /sys/block/sda/queue/scheduler
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… here are between ‘deadline’ and ‘noop’. Deadline is an active scheduler, and noop simply means IO will be handled without rescheduling…. Two steps here: echo noop > /sys/block/sda/queue/scheduler # update the scheduler in realtime And to make it permanent, add ‘elevator…
Post: Living with backups
November 6, 2008 By 28 Comments
… one-liners) On Linux there is also a utility called ionice. It allows to affect how I/O scheduler will be dealing… scheduler: # for device in `ls /sys/block` ; do if [ -f /sys/block/$device/queue/scheduler ] ; then \ echo “cfq” > /sys/block/$device/queue/scheduler ; fi ; done # cat /sys/block/sd?/queue/scheduler noop anticipatory deadline…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 17 Comments
… wrong. Q10: When Innodb decides to schedule sequential read-ahead, random read ahead ? HT: InnoDB schedules a sequential read-ahead when it… in an ascending order of the file address, then InnoDB schedules the read of all the 64 pages of the extent… global MySQL Server option, though it may have problems on Linux if you lock very large portion of physical memory. There…
Post: Performance impact of complex queries
January 17, 2007 By 11 Comments
… milliseconds you would expect disk IO to take. Scheduling Issues OS Disk IO schedules may also “help” in this case. Number of… willing to take. Especially some older disk schedulers could be poor. I remember in Linux 2.4 times I could make single… for directory with couple of files. In recent Linux Kernels deadline or cfq IO schedulers should be better with this. So what…
Comment: Linux schedulers in tpcc like benchmark
January 31, 2009 By 19 Comments
… based on the (very naive and unverified) believing that Linux I/O schedulers do reorder based on kernel’s page cache content… latency in the discussion (and also queues size/depths); indeed scheduling is not only about aggregating write requests and bulk performances… to reorder properly before cache being filled up. If so, scheduler added complexity may be even more a waste, but in…
