linux-kernel - Re: deadline unfairness

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 22 Mar 2008 23:09:27 +1100
From:	Aaron Carroll <aaronc@...ato.unsw.edu.au>
To:	Bernd Schubert <bernd-schubert@....de>
CC:	linux-kernel@...r.kernel.org
Subject: Re: deadline unfairness

Bernd Schubert wrote:
> Hello,
> 
> some it seems the deadline scheduler is rather unfair. Below is an example
> of md-raid6 initialization of md3, md4 and md5. All three md-devices
> do share the same blockdevices (we have patched md to allow
> parallel rebuild of shared block devices, since for us the cpu is the 
> bottleneck and not the block device).
> 
> All rebuilds started basically at the same time, as you can see, md3 is already
> done and now md4 rebuilds substantially faster than md5.
> [..]
> This is basically with a 2.6.22 kernel + lustre + md-backports, but nothing
> done to the scheduler.

Hi Bernd,

There is a deadline bug in pre-2.6.24 kernels where lower-sector requests can starve
higher-sector requests; you might be hitting this bug.  It was fixed by commit:
    6f5d8aa6382eef2b26032c88656270bdae7f0c42


 -- Aaron


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/