linux-kernel - Re: IO latency

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Message-ID: <9b1675090906122048o35698c09x13cc7cf7650ac9ae@mail.gmail.com>
Date:	Fri, 12 Jun 2009 21:48:41 -0600
From:	"Trenton D. Adams" <trenton.d.adams@...il.com>
To:	Theodore Tso <tytso@....edu>,
	"Trenton D. Adams" <trenton.d.adams@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: IO latency - a special case

Sorry I didn't reply earlier.  I got busy with some server troubles and such.

On Thu, Jun 11, 2009 at 1:11 PM, Theodore Tso<tytso@....edu> wrote:
> On Sat, Jun 06, 2009 at 09:14:43PM -0600, Trenton D. Adams wrote:
>> I'm back into doing some Java development, and it's happening again.
>> I'm running 2.6.30-rc7, and I did a SysReq+T, I hope this is helpful.
>> I've attached a txt.gz file, because it's 367K to my
>> /var/log/messages.
>>
>> The important stuff, I believe, is the Java related stuff.  As a quick
>> refresher to this problem, it appears to be related to how my Java IDE
>> saves the file, and perhaps something doesn't release the futex right
>> away?
>
> Have you checked your memory usage via SysReq-m, or /proc/meminfo or
> simply using "free".  I'm seeing a lot of processes in do_page_fault,
> which is interesting, especially in the non-Java processes.

I wasn't even aware of a SysReq-m.  I'll try that next time.  <rant>I
do wish the Macbook had a hard drive activity light *rolls
eyes*.</rant>

>
> Back in April, your vmstat output didn't show much swapping activity,
> but maybe there was more paging activity that didn't show up there?

Not sure I understand.  Paging without swapping?  I thought they were
one in the same, please explain; it's been a long time since I studied
kernel related theory.

>
>> I've also seen these symptoms previously...
>>
>> 1. Problem arises, I Ctrl-C the process when I notice the system
>> getting really sluggish.
>> 2. Start process again, and it locks up the machine for about an hour
>
> What sort of process where you typicalling trying to kill using ^C?

It's maven, which spawns javac (java compiler), as well as does
various other tasks such as making connections to the Internet, local
directories, etc.
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