[PATCH] ppc64: iSeries legacy model emulation of PURR

Here's a patch to extend the current Linux on Power support for PURR to
legacy IBM iSeries servers (pre-Power5 processor models).  This patch
enables the reporting of timebase metrics to reflect physical processor
utilization in a system running multiple logical partitions which share the
same physical processors.

The patch simply uses existing user interfaces for Linux IBM Power5 based
servers to report data already collected by the hypervisor.  The values
reported with each call are running values in units of the system timebase.
 The calculation of physical processor utilization results from two samples
(purr1 and purr2) differing by a know interval (time) such that:

    physical utilization = (purr2 - purr1) / (time * number of procs *
timebase)

where the number of procs and timebase can be obtained from /proc/cpuinfo.

Applications have been written to the interface already defined and these
applications have value back on the legacy iSeries models.

Signed-off by: Jeff Scheel (scheel at vnet.ibm.com)
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc64/kernel/lparcfg.c

@@ -34,7 +34,7 @@
 #include <asm/rtas.h>
 #include <asm/system.h>
 
-#define MODULE_VERS "1.4"
+#define MODULE_VERS "1.5"
 #define MODULE_NAME "lparcfg"
 
 /* #define LPARCFG_DEBUG */
@@ -70,6 +70,28 @@ static struct proc_dir_entry *proc_ppc64_lparcfg;
 
 #ifdef CONFIG_PPC_ISERIES
 
+/*
+ * For iSeries legacy systems, the PPA purr function is available from the
+ * xEmulatedTimeBase field in the paca.
+ */
+static unsigned long get_purr(void)
+{
+	unsigned long sum_purr = 0;
+	int cpu;
+	struct paca_struct *lpaca;
+
+	for_each_cpu(cpu) {
+		lpaca = paca + cpu;
+		sum_purr += lpaca->xLpPaca.xEmulatedTimeBase;
+
+#ifdef PURR_DEBUG
+		printk(KERN_INFO "get_purr for cpu (%d) has value (%ld) \n",
+			cpu, lpaca->xLpPaca.xEmulatedTimeBase);
+#endif
+	}
+	return sum_purr;
+}
+
 #define lparcfg_write NULL
 
 /* 
@@ -81,6 +103,9 @@ static int lparcfg_data(struct seq_file *m, void *v)
 	int shared, entitled_capacity, max_entitled_capacity;
 	int processors, max_processors;
 	struct paca_struct *lpaca = get_paca();
+	unsigned long purr = get_purr();
+
+	seq_printf(m, "%s %s \n", MODULE_NAME, MODULE_VERS);
 
 	shared = (int)(lpaca->lppaca_ptr->xSharedProc);
 	seq_printf(m, "serial_number=%c%c%c%c%c%c%c\n",
@@ -131,6 +156,7 @@ static int lparcfg_data(struct seq_file *m, void *v)
 		seq_printf(m, "pool_capacity=%d\n",
 			   (int)(HvLpConfig_getNumProcsInSharedPool(pool_id) *
 				 100));
+		seq_printf(m, "purr=%ld\n", purr);
 	}
 
 	seq_printf(m, "shared_processor_mode=%d\n", shared);