Commit aba76fdb authored Dec 10, 2006 by Andrew Morton Committed by Linus Torvalds Dec 10, 2006

[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: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus 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,

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