[PATCH] iSeries legacy model emulation of PURR

From: Jeff Scheel
Date: Thu Nov 11 2004 - 10:01:12 EST


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.

Please consider this patch for inclusion. It has been reviewed by Stephen.

Signed-off by: Jeff Scheel (scheel at vnet.ibm.com)

--- linuxppc-2.6.10_rc1.orig/arch/ppc64/kernel/lparcfg.c 2004-11-09 07:03:43.354383000 -0600
+++ linuxppc-2.6.10_rc1/arch/ppc64/kernel/lparcfg.c 2004-11-10 10:38:47.904484533 -0600
@@ -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 @@


+ * 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);
+ }
+ return sum_purr;
#define lparcfg_write NULL

/* @@ -81,6 +103,9 @@
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 @@
seq_printf(m, "pool_capacity=%d\n",
(int)(HvLpConfig_getNumProcsInSharedPool(pool_id) *
+ seq_printf(m, "purr=%ld\n", purr);

seq_printf(m, "shared_processor_mode=%d\n", shared);

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