… point for research, I think there some serialization in Linux software raid or Linux scheduler or on Adaptec hardware level. 2. Cards connected… table, randwr rows) 3. For cards connected in hardware raids, DEADLINE performs much worse than CFQ. Sequential reads: – For sequential reads you…
Post: Linux IO Schedulers and MySQL
January 30, 2007 By 7 Comments
…Linux IO Schedulers today which is quite interesting. It goes in details about schedulers and explains in which of workloads which of schedulers…time ago “AS” scheduler could be several times slower than deadline for MySQL … also means you’d better to perform IO scheduler benchmarks on mixed load with…
Post: Performance impact of complex queries
January 17, 2007 By 11 Comments
… 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 can… suffer from table locks reporting queries can affect web site performance dramatically. Sometimes instead of using slave you may use database…
Comment: FlashCache: tpcc workload
May 26, 2010 By 18 Comments
… just dies vs Deadline in OLTP workloads. See for example http://www.mysqlperformanceblog.com/2009/01/30/linux-schedulers-in-tpcc-like-benchmark/ Also we have bunch of customers cases when performance problem was healed just by one command echo deadline…
Post: Living with backups
November 6, 2008 By 28 Comments
…scheduled and executed which converts into slower queries execution and significantly degraded performance…can do with standard Linux tools like cp, …scheduler ; fi ; done # cat /sys/block/sd?/queue/scheduler noop anticipatory deadline [cfq] noop anticipatory deadline [cfq] noop anticipatory deadline…
Post: Setting up XFS on Hardware RAID -- the simple edition
December 16, 2011 By 9 Comments
…. Are there ways to squeeze more performance out of a server by dividing the… * 7813120 27344895 9765888 83 Linux /dev/sda3 27344896 856422399 414538752 83 Linux Several months ago …best choices here are between ‘deadline‘ and ‘noop’. Deadline is an active scheduler, and noop simply means …
Comment: Living with backups
November 18, 2008 By 28 Comments
… trick) though I tested various schedulers/setting do see how it affects the results. Originally running Linux-2.6.22, I had… to ridiculously low speed! – Using the deadline scheduler (which was the default) gives the best performance in all tested kernels – side read operation…
Post: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 11 Comments
… System Summary Report ############################## Platform | Linux Release | Ubuntu 10.04…. Other … # Disk Schedulers And Queue Size ############################# sda | [deadline] 128 # RAID …performance improvement is marginal however WB cache brings single thread random write performance…
Comment: Linux schedulers in tpcc like benchmark
October 27, 2009 By 19 Comments
…, Adaptive Read-ahead. Kernel 2.6.31.5 (Arch Linux). Very short recap with some numbers (40 simultaneous …scheduler) EXT2+noop: 97MB/s XFS+cfq: 30MB/s Some comments on this setup: – XFS beats EXT*, with EXT4 performing… difference. In this setup cfq seems close to broken. deadline is similar to noop…
