What’s the y-axis in the last graph? If you’re saying noop is 4x faster it probably depends on the RAID controller doing its own IO scheduling and CFQ confusing it… In our benchmarks noop always loses (obviously). Though on SSD it was faster.
Comment: How multiple disks can benefit for single client workload ?
April 29, 2008 By 4 Comments
Peter, Do you have any posts that compare filesystem and IO schedulers, and perhaps a SATA vs. SCSI comparison?
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 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…. I thought Innodb will make sure to schedule synchronous wait in front if read-ahead IO has not been started already. The…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
… is already free for grabs but os has not yet scheduled thread so it could proceed with execution. The second piece… for any of these variables is indication of IO bound workload. Note however – IO requests submited by threads executing requests are not… is currently active, state of Innodb main thread which controls scheduling of number of system operations – flushing dirty pages, checkpointing, purging…
Comment: Living with backups
July 1, 2009 By 28 Comments
… question there. Nice value affects only processor scheduler and has no effect on IO-intensive tasks. IO classes (ionice) works only with CFQ… the Anticipatory scheduler, however it should be even worse by design; Anticipatory should make Mysql wait even more on IO expecting sequential reads; while it will likely make random requests. Once you find the fastest scheduler for your…
Post: Battery Learning still problem many years after
February 10, 2011 By 7 Comments
… hundred dollars more per server just to avoid nightmare of scheduling learning cycles. I’m surprised it takes so many years… for testing. I recommend this testing as part of complex IO subsystem performance testing – if you have RAID check what performance… is going through the process. Second. Schedule it. Most systems would be much better with scheduled learning during the night or weekend…
Comment: kernel_mutex problem cont. Or triple your throughput
December 4, 2011 By 10 Comments
… low and when there are heavy batch jobs which are IO bound and would benefit from a lot higher innodb_thread… be to some form of IO aware thread scheduling for whole MySQL not just Innodb where you can schedule something else to run when thread is to be blocked on disk/network IO, locks etc.
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…_purge_threadsblogpercona.commanual innodb_read_ahead_thresholdblogpercona.commanual innodb_read_io_threadsblogpercona.commanual innodb_replication_delayblogpercona.commanual innodb_rollback_on_timeoutblogpercona… innodb_use_sys_mallocblogpercona.commanual innodb_versionblogpercona.commanual innodb_write_io_threadsblogpercona.commanual insert_idblogpercona.commanual interactive_timeoutblogpercona.commanual join_buffer…
Post: How multiple disks can benefit for single client workload ?
April 26, 2008 By 4 Comments
… (or row portions) or having these “touches” resolved as logical IO rather than physical. There is still locking ,networking etc to… as not as I typically use these terms. For me IO is IO bound workload – disks are moving and CPU sits idle… to flush – it happens in the background on its own schedule. Such flush activity is another activity which will happen in…
Post: The new cool MySQL patch has landed! Check your queries performance!
October 31, 2007 By 16 Comments
…_pages_distinct: 20 InnoDB_IO_r_ops is the counter for the number of page read operations scheduled. The acutal number of…, unfortunatelly there is no good way to measure that. InnoDB_IO_r_bytes is the corresponding value in bytes. With InnoDB…_filesort: No Merge_passes: 0 # InnoDB_IO_r_ops: 19 InnoDB_IO_r_bytes: 311296 InnoDB_IO_r_wait: 0.382176 # InnoDB_rec…
