linux-kernel - Re: [PATCHSET] blk-throttle: implement proper hierarchy support

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]

Message-ID: <20130503185751.GA22860@mtj.dyndns.org>
Date:	Fri, 3 May 2013 11:57:51 -0700
From:	Tejun Heo <tj@...nel.org>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	Jens Axboe <axboe@...nel.dk>, lkml <linux-kernel@...r.kernel.org>,
	Li Zefan <lizefan@...wei.com>,
	containers@...ts.linux-foundation.org,
	Cgroups <cgroups@...r.kernel.org>
Subject: Re: [PATCHSET] blk-throttle: implement proper hierarchy support

On Fri, May 03, 2013 at 01:56:52PM -0400, Vivek Goyal wrote:
> > Yeah, I think that's what *should* be happening but not what I'm
> > seeing.  I'm seeing ~15% penalty.
> 
> What test are you running. I am running a simple dd with directIO and
> I am not seeing any penalty.

Combination of dd and a test program that I've been using for some
while which can generate concurrent direct random IOs.  Attaching the
source code for the latter.

> # set limit to 1000000 bytes/second both in parent and child cgroup
> # dd if=/dev/vdb of=/dev/null iflag=direct
> 
> I will capture blktrace and analyze it though to understand better
> what's happening.

Try using larger block size.  It looks like dispatch windows being
reset depending on timing is hurting the overall bandwidth.  It
becomes pronounced with larger IOs.

Thanks.

-- 
tejun
--
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/