linux-kernel - Re: multi-second application stall in open()

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: <20120626204322.GV3869@google.com>
Date:	Tue, 26 Jun 2012 13:43:22 -0700
From:	Tejun Heo <tj@...nel.org>
To:	Josh Hunt <joshhunt00@...il.com>
Cc:	Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org,
	Vivek Goyal <vgoyal@...hat.com>
Subject: Re: multi-second application stall in open()

Hello,

On Tue, Jun 26, 2012 at 10:18:04AM -0500, Josh Hunt wrote:
> Do you have any suggestions on how to debug this?
> 
> I did "perf record -a -e workqueue:*" and grabbed some tracepoint
> data, but it's hard to correlate when these events are occurring in
> the blktrace logs. Will keep investigating.

Yeah, as Vivek said, it would be better to get both traces through
perf instead of using blktrace.  queue_work and execute_start TPs
print out the function pointer.  Only printing out entries which match
the unplug_work would reduce a lot of noise - you can grep
cfq_kick_queue's address from /proc/kallsyms and set up
/sys/kernel/debug/tracing/events/workqueue/EVENT/filter - "echo
function==0xFUNCADDR > /sys/kernel/debug.../filter".  Not sure how to
do that with perf tho.

Ooh, you posted another message.  Will continue there.

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/