From: NeilBrown <neilb@suse.de>
To: Ethan Wilson <ethan.wilson@shiftmail.org>
Cc: "linux-raid@vger.kernel.org" <linux-raid@vger.kernel.org>
Subject: Re: RAID456 direct I/O write performance
Date: Tue, 9 Sep 2014 13:24:31 +1000 [thread overview]
Message-ID: <20140909132431.24456db1@notabene.brown> (raw)
In-Reply-To: <5408D5CC.101@shiftmail.org>
[-- Attachment #1: Type: text/plain, Size: 899 bytes --]
On Thu, 04 Sep 2014 23:12:44 +0200 Ethan Wilson <ethan.wilson@shiftmail.org>
wrote:
> OTOH I would like to ask kernel experts one thing if I may: does anybody
> know a way to get a stack trace for a process which is currently running
> in kernel mode and is running NOW on a CPU and it is not stopped waiting
> in a queue? I know about /proc/pid/stack but that one shows
> 0xffffffffffffffff for such a case. Being able to do that would help to
> answer the above question too...
The contents of the stack would change while it was being inspected, so it
would be impossible to get a meaningful trace.
Maybe you could disable all but one CPU. Then whenever you try to look at
the stack of another process it must have scheduled and so will have a
stable visible stack...
Or maybe you would use "perf record -g" to get some stack information, I'm
not sure.
NeilBrown
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 828 bytes --]
prev parent reply other threads:[~2014-09-09 3:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-04 16:23 RAID456 direct I/O write performance Markus Stockhausen
2014-09-04 16:30 ` AW: " Markus Stockhausen
2014-09-04 21:12 ` Ethan Wilson
2014-09-05 18:06 ` AW: " Markus Stockhausen
2014-09-06 19:46 ` Markus Stockhausen
2014-09-09 3:24 ` NeilBrown [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140909132431.24456db1@notabene.brown \
--to=neilb@suse.de \
--cc=ethan.wilson@shiftmail.org \
--cc=linux-raid@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.