Mailinglist Archive: opensuse-kernel (85 mails)

["M. Edward (Ed) Borasky" <znmeb@xxxxxxxxxxxxxxxxxxxx>]

blktrace / seekwatcher are good places to start. See

https://github.com/znmeb/LinuxCon2009/tree/master/Linux_Server_Profiling_Using_Open_Source_Tools_for_Bottleneck_Analysis
https://github.com/znmeb/LinuxCon2009/tree/master/Modeling_the_Linux_Block_I-O_Layer_For_Enterprise_Applications

On Wed, Jan 18, 2012 at 1:32 AM,  <rst@xxxxxxxxxxxxx> wrote:
> Hi y'all,
>
> I've been directed here by the opensuse forums about a problem we are having 
> with our server since we upgraded from opensuse 11.2 (kernel 2.6.31 I believe)
> to 12.1.
>
> The problem is that one process can hog all disk io and starves others. For 
> example progress database restore of multi GB DB  starves all others for 
> example mysqld.
> We see latencies on fsync for mysqld of 15s + with cfq block io scheduler. 
> Still 5s+ with deadline block io scheduler and read_expire reduced to 20ms.
>
> Been unable to reduce latency for other processes any further.
>
> Our guess to the culprit is that the improvement that was made in 2.6.37 for 
> smp ext4 block io throughput (300-400% according to
> Linux 2 6 37 - Linux Kernel Newbies ) has made it possible for one process to 
> be that fast and created this starvation problem.
>
> Or maybe some kernel bug.
>
> Anybody have any pointers about how to reign in disk-io hogs in 3.1?
>
>
> best regards
>
>
> remo
>
> Some info about the Server:
> Dell T710 with 2 Xeon 6 core procs, 48GB Memory. 6x300GB Disks in RAID10 on a 
> H700 Raid Controller.
>
> We didn't mess with many default Suse Kernel values. Except swapiness, 
> default blocksize of Tape Driver, Max Semaphore and Shared Memory Segment
> Values ( /proc/sys/kernel/shmmax shmmni shmall). And of course the 
> ioscheduler as deadline scheduler makes the system less unusable...
>
> I'll gladly provide any other info y'all might need to help us improve this 
> starvation issue.
>
> --
> To unsubscribe, e-mail: opensuse-kernel+unsubscribe@xxxxxxxxxxxx
> To contact the owner, e-mail: opensuse-kernel+owner@xxxxxxxxxxxx



-- 
http://twitter.com/znmeb http://borasky-research.net

"A mathematician is a device for turning coffee into theorems." -- Paul Erdős
--
To unsubscribe, e-mail: opensuse-kernel+unsubscribe@xxxxxxxxxxxx
To contact the owner, e-mail: opensuse-kernel+owner@xxxxxxxxxxxx