linux-kernel - taskstats and /proc/.../io asymmetry?

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-next>] [day] [month] [year] [list]

Date:	Wed, 14 May 2008 06:59:25 -0400
From:	Mark Seger <Mark.Seger@...com>
To:	Shailabh Nagar <nagar@...son.ibm.com>,
	Balbir Singh <balbir@...ibm.com>, Jes Sorensen <jes@....com>,
	Chris Sturtivant <csturtiv@....com>, Tony Ernst <tee@....com>,
	Guillaume Thouvenin <guillaume.thouvenin@...l.net>,
	Jay Lan <jlan@...r.sgi.com>, linux-kernel@...r.kernel.org
Subject: taskstats and /proc/.../io asymmetry?

If you look at /proc/pid/stat, you can get the total CPU consumed by a 
process.  If you look at /proc/pid/task/tid/stat you can get the cpu 
consumed by a thread and if the tid is that of the parent you only gets 
its consumption as opposed to all its children.

I was surprised to see that the way process I/O is reported doesn't 
follow this model.  There are no /prod/pid/task/tid/io entries but 
rather you need to look in /proc/tid/io.  While I view this as a minor 
inconvenience, I can certainly live with it.  However, /proc/pid/io does 
not show the aggregate I/O numbers for the whole process and that both 
surprises and disappoints.  This means if I have a process that starts a 
bunch of worker threads that do the real work and I want to find the top 
I/O consumers I can't simply walk the /proc/pid tree but rather have to 
look at all the threads of each process and add them up.

Or am I missing something?

-mark

--
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/