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Commit aba76fdb authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds
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[PATCH] io-accounting: report in procfs 



Add a simple /proc/pid/io to show the IO accounting fields.

Maybe this shouldn't be merged in mainline - the preferred reporting channel
is taskstats.  But given the poor state of our userspace support for
taskstats, this is useful for developer-testing, at least.  And it improves
the changes that the procps developers will wire it up into top(1).  Opinions
are sought.

The patch also wires up the existing IO-accounting fields.

It's a bit racy on 32-bit machines: if process A reads process B's
/proc/pid/io while process B is updating one of those 64-bit counters, process
A could see an intermediate result.

Cc: Jay Lan <jlan@sgi.com>
Cc: Shailabh Nagar <nagar@watson.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Chris Sturtivant <csturtiv@sgi.com>
Cc: Tony Ernst <tee@sgi.com>
Cc: Guillaume Thouvenin <guillaume.thouvenin@bull.net>
Cc: David Wright <daw@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 98c4d57d

fs/proc/base.c

+24 −0
Original line number Diff line number Diff line
@@ -1804,6 +1804,27 @@ static int proc_base_fill_cache(struct file *filp, void *dirent, filldir_t filld 
				proc_base_instantiate, task, p);

}



#ifdef CONFIG_TASK_IO_ACCOUNTING

static int proc_pid_io_accounting(struct task_struct *task, char *buffer)

{

	return sprintf(buffer,

			"rchar: %llu\n"

			"wchar: %llu\n"

			"syscr: %llu\n"

			"syscw: %llu\n"

			"read_bytes: %llu\n"

			"write_bytes: %llu\n"

			"cancelled_write_bytes: %llu\n",

			(unsigned long long)task->rchar,

			(unsigned long long)task->wchar,

			(unsigned long long)task->syscr,

			(unsigned long long)task->syscw,

			(unsigned long long)task->ioac.read_bytes,

			(unsigned long long)task->ioac.write_bytes,

			(unsigned long long)task->ioac.cancelled_write_bytes);

}

#endif



/*

 * Thread groups

 */
@@ -1855,6 +1876,9 @@ static struct pid_entry tgid_base_stuff[] = { 
#ifdef CONFIG_FAULT_INJECTION

	REG("make-it-fail", S_IRUGO|S_IWUSR, fault_inject),

#endif

#ifdef CONFIG_TASK_IO_ACCOUNTING

	INF("io",	S_IRUGO, pid_io_accounting),

#endif

};



static int proc_tgid_base_readdir(struct file * filp,