[PATCH 0/3] powerpc: Instrument Hypervisor Calls

[PATCH 0/3] powerpc: Instrument Hypervisor Calls

[Mike Kravetz]

This patch series adds instrumentation to Hypervisor calls.  Code and
ideas were taken from the patch set provided by Christopher Yeoh.

The idea is to put all instrumentation code behind a configuration
option so that it can easily be added/removed.  The instrumentation
code is kept to a minimum in the hopes that it's impact to performance
will not be noticed.  Statistics are made available via files in sysfs.

-- 
Mike

[PATCH 1/3] powerpc: Instrument Hypervisor Calls: merge headers

[Mike Kravetz]

Move all the Hypervisor call definitions to to a single header file.

-- 
Signed-off-by: Mike Kravetz <kravetz@us.ibm.com>


diff -Naupr linux-2.6.17-rc6/drivers/net/ibmveth.h linux-2.6.17-rc6.work/drivers/net/ibmveth.h
--- linux-2.6.17-rc6/drivers/net/ibmveth.h	2006-06-06 00:57:02.000000000 +0000
+++ linux-2.6.17-rc6.work/drivers/net/ibmveth.h	2006-06-13 21:35:10.000000000 +0000
@@ -41,16 +41,6 @@
 #define IbmVethMcastRemoveFilter     0x2UL
 #define IbmVethMcastClearFilterTable 0x3UL
 
-/* hcall numbers */
-#define H_VIO_SIGNAL             0x104
-#define H_REGISTER_LOGICAL_LAN   0x114
-#define H_FREE_LOGICAL_LAN       0x118
-#define H_ADD_LOGICAL_LAN_BUFFER 0x11C
-#define H_SEND_LOGICAL_LAN       0x120
-#define H_MULTICAST_CTRL         0x130
-#define H_CHANGE_LOGICAL_LAN_MAC 0x14C
-#define H_FREE_LOGICAL_LAN_BUFFER 0x1D4
-
 /* hcall macros */
 #define h_register_logical_lan(ua, buflst, rxq, fltlst, mac) \
   plpar_hcall_norets(H_REGISTER_LOGICAL_LAN, ua, buflst, rxq, fltlst, mac)
diff -Naupr linux-2.6.17-rc6/include/asm-powerpc/hvcall.h linux-2.6.17-rc6.work/include/asm-powerpc/hvcall.h
--- linux-2.6.17-rc6/include/asm-powerpc/hvcall.h	2006-06-06 00:57:02.000000000 +0000
+++ linux-2.6.17-rc6.work/include/asm-powerpc/hvcall.h	2006-06-13 21:35:10.000000000 +0000
@@ -155,9 +155,15 @@
 #define H_VIO_SIGNAL		0x104
 #define H_SEND_CRQ		0x108
 #define H_COPY_RDMA		0x110
+#define H_REGISTER_LOGICAL_LAN	0x114
+#define H_FREE_LOGICAL_LAN	0x118
+#define H_ADD_LOGICAL_LAN_BUFFER 0x11C
+#define H_SEND_LOGICAL_LAN	0x120
+#define H_MULTICAST_CTRL	0x130
 #define H_SET_XDABR		0x134
 #define H_STUFF_TCE		0x138
 #define H_PUT_TCE_INDIRECT	0x13C
+#define H_CHANGE_LOGICAL_LAN_MAC 0x14C
 #define H_VTERM_PARTNER_INFO	0x150
 #define H_REGISTER_VTERM	0x154
 #define H_FREE_VTERM		0x158
@@ -187,11 +193,14 @@
 #define H_GET_HCA_INFO          0x1B8
 #define H_GET_PERF_COUNT        0x1BC
 #define H_MANAGE_TRACE          0x1C0
+#define H_FREE_LOGICAL_LAN_BUFFER 0x1D4
 #define H_QUERY_INT_STATE       0x1E4
 #define H_POLL_PENDING		0x1D8
 #define H_JOIN			0x298
 #define H_ENABLE_CRQ		0x2B0
 
+#define MAX_HCALL_OPCODES	(H_ENABLE_CRQ >> 2)
+
 #ifndef __ASSEMBLY__
 
 /* plpar_hcall() -- Generic call interface using above opcodes

[PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers

[Mike Kravetz]

Add wrappers which perform the actual hypervisor call instrumentation.

-- 
Signed-off-by: Mike Kravetz <kravetz@us.ibm.com>


diff -Naupr linux-2.6.17-rc6/arch/powerpc/Kconfig.debug linux-2.6.17-rc6.work/arch/powerpc/Kconfig.debug
--- linux-2.6.17-rc6/arch/powerpc/Kconfig.debug	2006-06-06 00:57:02.000000000 +0000
+++ linux-2.6.17-rc6.work/arch/powerpc/Kconfig.debug	2006-06-13 21:39:24.000000000 +0000
@@ -18,6 +18,16 @@ config DEBUG_STACK_USAGE
 
 	  This option will slow down process creation somewhat.
 
+config HCALL_STATS
+	bool "Hypervisor call instrumentation"
+	depends on PPC_PSERIES
+	help
+	  Adds code to keep track of number of hypervisor calls made and
+	  the amount of time spent in hypervisor calls.
+
+	  This option will add a small amount of overhead to all hypervisor
+	  calls.
+
 config DEBUGGER
 	bool "Enable debugger hooks"
 	depends on DEBUG_KERNEL
diff -Naupr linux-2.6.17-rc6/arch/powerpc/platforms/pseries/Makefile linux-2.6.17-rc6.work/arch/powerpc/platforms/pseries/Makefile
--- linux-2.6.17-rc6/arch/powerpc/platforms/pseries/Makefile	2006-06-06 00:57:02.000000000 +0000
+++ linux-2.6.17-rc6.work/arch/powerpc/platforms/pseries/Makefile	2006-06-13 21:39:24.000000000 +0000
@@ -9,3 +9,4 @@ obj-$(CONFIG_EEH)	+= eeh.o eeh_cache.o e
 
 obj-$(CONFIG_HVC_CONSOLE)	+= hvconsole.o
 obj-$(CONFIG_HVCS)		+= hvcserver.o
+obj-$(CONFIG_HCALL_STATS)	+= hvCall_inst.o
diff -Naupr linux-2.6.17-rc6/arch/powerpc/platforms/pseries/hvCall.S linux-2.6.17-rc6.work/arch/powerpc/platforms/pseries/hvCall.S
--- linux-2.6.17-rc6/arch/powerpc/platforms/pseries/hvCall.S	2006-06-06 00:57:02.000000000 +0000
+++ linux-2.6.17-rc6.work/arch/powerpc/platforms/pseries/hvCall.S	2006-06-13 21:39:24.000000000 +0000
@@ -25,7 +25,11 @@
 			unsigned long *out2,		R9
 			unsigned long *out3);		R10
  */
+#ifdef CONFIG_HCALL_STATS
+_GLOBAL(plpar_hcall_base)
+#else
 _GLOBAL(plpar_hcall)
+#endif
 	HMT_MEDIUM
 
 	mfcr	r0
@@ -52,7 +56,15 @@ _GLOBAL(plpar_hcall)
 
 
 /* Simple interface with no output values (other than status) */
+#ifdef CONFIG_HCALL_STATS
 _GLOBAL(plpar_hcall_norets)
+	b	plpar_hcall_norets_C
+
+
+_GLOBAL(plpar_hcall_norets_base)
+#else
+_GLOBAL(plpar_hcall_norets)
+#endif
 	HMT_MEDIUM
 
 	mfcr	r0
@@ -76,7 +88,11 @@ _GLOBAL(plpar_hcall_norets)
 			unsigned long arg8,		112(R1)
 			unsigned long *out1);		120(R1)
  */
+#ifdef CONFIG_HCALL_STATS
+_GLOBAL(plpar_hcall_8arg_2ret_base)
+#else
 _GLOBAL(plpar_hcall_8arg_2ret)
+#endif
 	HMT_MEDIUM
 
 	mfcr	r0
@@ -102,7 +118,11 @@ _GLOBAL(plpar_hcall_8arg_2ret)
 		 	unsigned long *out3,		R10
 		 	unsigned long *out4);		112(R1)
  */
+#ifdef CONFIG_HCALL_STATS
+_GLOBAL(plpar_hcall_4out_base)
+#else
 _GLOBAL(plpar_hcall_4out)
+#endif
 	HMT_MEDIUM
 
 	mfcr	r0
@@ -144,7 +164,11 @@ _GLOBAL(plpar_hcall_4out)
 			 unsigned long *out6,		102(R1)
 			 unsigned long *out7);		100(R1)
 */
+#ifdef CONFIG_HCALL_STATS
+_GLOBAL(plpar_hcall_7arg_7ret_base)
+#else
 _GLOBAL(plpar_hcall_7arg_7ret)
+#endif
 	HMT_MEDIUM
 
 	mfcr	r0
@@ -193,7 +217,11 @@ _GLOBAL(plpar_hcall_7arg_7ret)
 			 unsigned long *out8,		 94(R1)
 		         unsigned long *out9,            92(R1)
 */
+#ifdef CONFIG_HCALL_STATS
+_GLOBAL(plpar_hcall_9arg_9ret_base)
+#else
 _GLOBAL(plpar_hcall_9arg_9ret)
+#endif
 	HMT_MEDIUM
 
 	mfcr	r0
diff -Naupr linux-2.6.17-rc6/arch/powerpc/platforms/pseries/hvCall_inst.c linux-2.6.17-rc6.work/arch/powerpc/platforms/pseries/hvCall_inst.c
--- linux-2.6.17-rc6/arch/powerpc/platforms/pseries/hvCall_inst.c	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.17-rc6.work/arch/powerpc/platforms/pseries/hvCall_inst.c	2006-06-13 21:39:24.000000000 +0000
@@ -0,0 +1,239 @@
+/*
+ * Copyright (C) 2006 Mike Kravetz IBM Corporation
+ *
+ * Hypervisor Call Instrumentation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/percpu.h>
+#include <asm/hvcall.h>
+
+DEFINE_PER_CPU(struct hcall_stats[MAX_HCALL_OPCODES+1], hcall_stats);
+
+static inline void update_stats(unsigned long opcode, unsigned long t_before)
+{
+	unsigned long op_index= opcode >> 2;
+	struct hcall_stats *hs = &__get_cpu_var(hcall_stats[op_index]);
+
+	/* racey, but acceptable for non-critical stats */
+	hs->total_time += (mfspr(SPRN_PURR) - t_before);
+	hs->num_calls++;
+}
+
+extern long plpar_hcall_base (unsigned long opcode,
+                 unsigned long arg1,
+                 unsigned long arg2,
+                 unsigned long arg3,
+                 unsigned long arg4,
+                 unsigned long *out1,
+                 unsigned long *out2,
+                 unsigned long *out3);
+
+long plpar_hcall(unsigned long opcode,
+                 unsigned long arg1,
+                 unsigned long arg2,
+                 unsigned long arg3,
+                 unsigned long arg4,
+                 unsigned long *out1,
+                 unsigned long *out2,
+                 unsigned long *out3)
+{
+	long rc;
+	unsigned long t_before = mfspr(SPRN_PURR);
+
+	rc = plpar_hcall_base(opcode, arg1, arg2, arg3, arg4, out1, out2, out3);
+
+	update_stats(opcode, t_before);
+	return rc;
+}
+
+extern long plpar_hcall_norets_base(unsigned long opcode, ...);
+
+long plpar_hcall_norets_C(unsigned long opcode,
+				unsigned long arg1,
+				unsigned long arg2,
+				unsigned long arg3,
+				unsigned long arg4,
+				unsigned long arg5,
+				unsigned long arg6)
+{
+	long rc;
+	unsigned long t_before = mfspr(SPRN_PURR);
+
+	rc = plpar_hcall_norets_base(opcode, arg1, arg2, arg3, arg4, arg5,
+				     arg6);
+
+	update_stats(opcode, t_before);
+	return rc;
+}
+
+extern long plpar_hcall_8arg_2ret_base(unsigned long opcode,
+                           unsigned long arg1,
+                           unsigned long arg2,
+                           unsigned long arg3,
+                           unsigned long arg4,
+                           unsigned long arg5,
+                           unsigned long arg6,
+                           unsigned long arg7,
+                           unsigned long arg8,
+                           unsigned long *out1);
+
+long plpar_hcall_8arg_2ret(unsigned long opcode,
+                           unsigned long arg1,
+                           unsigned long arg2,
+                           unsigned long arg3,
+                           unsigned long arg4,
+                           unsigned long arg5,
+                           unsigned long arg6,
+                           unsigned long arg7,
+                           unsigned long arg8,
+                           unsigned long *out1)
+{
+	long rc;
+	unsigned long t_before = mfspr(SPRN_PURR);
+
+	rc = plpar_hcall_8arg_2ret_base(opcode, arg1, arg2, arg3, arg4, arg5,
+					arg6, arg7, arg8, out1);
+
+	update_stats(opcode, t_before);
+	return rc;
+}
+
+extern long plpar_hcall_4out_base(unsigned long opcode,
+                      unsigned long arg1,
+                      unsigned long arg2,
+                      unsigned long arg3,
+                      unsigned long arg4,
+                      unsigned long *out1,
+                      unsigned long *out2,
+                      unsigned long *out3,
+                      unsigned long *out4);
+
+long plpar_hcall_4out(unsigned long opcode,
+                      unsigned long arg1,
+                      unsigned long arg2,
+                      unsigned long arg3,
+                      unsigned long arg4,
+                      unsigned long *out1,
+                      unsigned long *out2,
+                      unsigned long *out3,
+                      unsigned long *out4)
+{
+	long rc;
+	unsigned long t_before = mfspr(SPRN_PURR);
+
+	rc = plpar_hcall_4out_base(opcode, arg1, arg2, arg3, arg4, out1,
+				   out2, out3, out4);
+
+	update_stats(opcode, t_before);
+	return rc;
+}
+
+extern long plpar_hcall_7arg_7ret_base(unsigned long opcode,
+                           unsigned long arg1,
+                           unsigned long arg2,
+                           unsigned long arg3,
+                           unsigned long arg4,
+                           unsigned long arg5,
+                           unsigned long arg6,
+                           unsigned long arg7,
+                           unsigned long *out1,
+                           unsigned long *out2,
+                           unsigned long *out3,
+                           unsigned long *out4,
+                           unsigned long *out5,
+                           unsigned long *out6,
+                           unsigned long *out7);
+
+long plpar_hcall_7arg_7ret(unsigned long opcode,
+                           unsigned long arg1,
+                           unsigned long arg2,
+                           unsigned long arg3,
+                           unsigned long arg4,
+                           unsigned long arg5,
+                           unsigned long arg6,
+                           unsigned long arg7,
+                           unsigned long *out1,
+                           unsigned long *out2,
+                           unsigned long *out3,
+                           unsigned long *out4,
+                           unsigned long *out5,
+                           unsigned long *out6,
+                           unsigned long *out7)
+{
+	long rc;
+	unsigned long t_before = mfspr(SPRN_PURR);
+
+	rc = plpar_hcall_7arg_7ret_base(opcode, arg1, arg2, arg3, arg4, arg5,
+					arg6, arg7, out1, out2, out3, out4,
+					out5, out6, out7);
+
+	update_stats(opcode, t_before);
+	return rc;
+}
+
+extern long plpar_hcall_9arg_9ret_base(unsigned long opcode,
+                           unsigned long arg1,
+                           unsigned long arg2,
+                           unsigned long arg3,
+                           unsigned long arg4,
+                           unsigned long arg5,
+                           unsigned long arg6,
+                           unsigned long arg7,
+                           unsigned long arg8,
+                           unsigned long arg9,
+                           unsigned long *out1,
+                           unsigned long *out2,
+                           unsigned long *out3,
+                           unsigned long *out4,
+                           unsigned long *out5,
+                           unsigned long *out6,
+                           unsigned long *out7,
+                           unsigned long *out8,
+                           unsigned long *out9);
+
+long plpar_hcall_9arg_9ret(unsigned long opcode,
+                           unsigned long arg1,
+                           unsigned long arg2,
+                           unsigned long arg3,
+                           unsigned long arg4,
+                           unsigned long arg5,
+                           unsigned long arg6,
+                           unsigned long arg7,
+                           unsigned long arg8,
+                           unsigned long arg9,
+                           unsigned long *out1,
+                           unsigned long *out2,
+                           unsigned long *out3,
+                           unsigned long *out4,
+                           unsigned long *out5,
+                           unsigned long *out6,
+                           unsigned long *out7,
+                           unsigned long *out8,
+                           unsigned long *out9)
+{
+	long rc;
+	unsigned long t_before = mfspr(SPRN_PURR);
+
+	rc = plpar_hcall_9arg_9ret_base(opcode, arg1, arg2, arg3, arg4, arg5,
+					arg6, arg7, arg8, arg9, out1, out2,
+					out3, out4, out5, out6, out7, out8,
+					out9);
+
+	update_stats(opcode, t_before);
+	return rc;
+}
diff -Naupr linux-2.6.17-rc6/include/asm-powerpc/hvcall.h linux-2.6.17-rc6.work/include/asm-powerpc/hvcall.h
--- linux-2.6.17-rc6/include/asm-powerpc/hvcall.h	2006-06-13 21:38:45.000000000 +0000
+++ linux-2.6.17-rc6.work/include/asm-powerpc/hvcall.h	2006-06-13 21:39:24.000000000 +0000
@@ -292,6 +292,13 @@ long plpar_hcall_9arg_9ret(unsigned long
 			   unsigned long *out8,
 			   unsigned long *out9);
 
+#ifdef CONFIG_HCALL_STATS
+struct hcall_stats {
+	unsigned long	num_calls;
+	unsigned long	total_time;
+};
+#endif /* CONFIG_HCALL_STATS */
+
 #endif /* __ASSEMBLY__ */
 #endif /* __KERNEL__ */
 #endif /* _ASM_POWERPC_HVCALL_H */

[PATCH 0/3] powerpc: Instrument Hypervisor Calls: add sysfs files

[Mike Kravetz]

Make statistics available via files in sysfs.

-- 
Signed-off-by: Mike Kravetz <kravetz@us.ibm.com>


diff -Naupr linux-2.6.17-rc6/arch/powerpc/kernel/sysfs.c linux-2.6.17-rc6.work/arch/powerpc/kernel/sysfs.c
--- linux-2.6.17-rc6/arch/powerpc/kernel/sysfs.c	2006-06-06 00:57:02.000000000 +0000
+++ linux-2.6.17-rc6.work/arch/powerpc/kernel/sysfs.c	2006-06-13 21:42:32.000000000 +0000
@@ -356,6 +356,39 @@ static ssize_t show_physical_id(struct s
 }
 static SYSDEV_ATTR(physical_id, 0444, show_physical_id, NULL);
 
+#ifdef CONFIG_HCALL_STATS
+DECLARE_PER_CPU(struct hcall_stats[MAX_HCALL_OPCODES+1], hcall_stats);
+
+static ssize_t show_hcall_stats(struct sys_device *dev, char *buf)
+{
+	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
+	struct hcall_stats *hs = per_cpu(hcall_stats, cpu->sysdev.id);
+	size_t rc = 0;
+	size_t b_written = 0;
+	size_t b_remain = PAGE_SIZE;
+	unsigned long i;
+
+	for (i=0; i<MAX_HCALL_OPCODES+1; i++){
+		if (!hs[i].num_calls)
+			continue;
+
+		b_written = snprintf(buf+rc, b_remain,
+				"%lu %lu %lu\n",
+				i<<2, hs[i].num_calls, hs[i].total_time);
+
+		if (b_written >= b_remain)
+			break;	/* end of buffer */
+
+		rc += b_written;
+		b_remain -= b_written;
+	}
+
+	return rc;
+}
+
+static SYSDEV_ATTR(hcall_stats, 0666, show_hcall_stats, NULL);
+#endif /* CONFIG_HCALL_STATS */
+
 static int __init topology_init(void)
 {
 	int cpu;
@@ -390,6 +423,9 @@ static int __init topology_init(void)
 			register_cpu(c, cpu, parent);
 
 			sysdev_create_file(&c->sysdev, &attr_physical_id);
+#ifdef CONFIG_HCALL_STATS
+			sysdev_create_file(&c->sysdev, &attr_hcall_stats);
+#endif
 		}
 
 		if (cpu_online(cpu))

Re: [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers

[Arnd Bergmann]

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CglBcm5kIDw+PAo=

Re: [PATCH 0/3] powerpc: Instrument Hypervisor Calls: add sysfs files

[Nathan Lynch]

Hi Mike-

> +#ifdef CONFIG_HCALL_STATS
> +DECLARE_PER_CPU(struct hcall_stats[MAX_HCALL_OPCODES+1], hcall_stats);
> +
> +static ssize_t show_hcall_stats(struct sys_device *dev, char *buf)
> +{
> +	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
> +	struct hcall_stats *hs = per_cpu(hcall_stats, cpu->sysdev.id);
> +	size_t rc = 0;
> +	size_t b_written = 0;
> +	size_t b_remain = PAGE_SIZE;
> +	unsigned long i;
> +
> +	for (i=0; i<MAX_HCALL_OPCODES+1; i++){

Coding style:
                  i < MAX_HCALL_OPCODES + 1

> +		if (!hs[i].num_calls)
> +			continue;
> +
> +		b_written = snprintf(buf+rc, b_remain,
> +				"%lu %lu %lu\n",
> +				i<<2, hs[i].num_calls, hs[i].total_time);
> +
> +		if (b_written >= b_remain)
> +			break;	/* end of buffer */
> +
> +		rc += b_written;
> +		b_remain -= b_written;
> +	}
> +
> +	return rc;
> +}

This flagrantly violates the one-value-per-file rule for sysfs. ;)

Maybe debugfs or some other mechanism would be more appropriate.

Do we not run the risk of having output truncated after the system has
been up for a while and has done a few million hcalls?

> +
> +static SYSDEV_ATTR(hcall_stats, 0666, show_hcall_stats, NULL);

Mode should be 0444 or 0400, no need to have write permissions.

> +#endif /* CONFIG_HCALL_STATS */
> +
>  static int __init topology_init(void)
>  {
>  	int cpu;
> @@ -390,6 +423,9 @@ static int __init topology_init(void)
>  			register_cpu(c, cpu, parent);
>  
>  			sysdev_create_file(&c->sysdev, &attr_physical_id);
> +#ifdef CONFIG_HCALL_STATS
> +			sysdev_create_file(&c->sysdev, &attr_hcall_stats);
> +#endif

Let's not create the file on non-lpar systems.

[PATCH 0/3] powerpc: Instrument Hypervisor Calls: add sysfs files

[Dave C Boutcher]

On Tue, 13 Jun 2006 20:54:20 -0700, Mike Kravetz <kravetz@us.ibm.com> said:
> 
> Make statistics available via files in sysfs.
> -- 
> Signed-off-by: Mike Kravetz <kravetz@us.ibm.com>
> 
> 
> diff -Naupr linux-2.6.17-rc6/arch/powerpc/kernel/sysfs.c linux-2.6.17-rc6.work/arch/powerpc/kernel/sysfs.c
> --- linux-2.6.17-rc6/arch/powerpc/kernel/sysfs.c	2006-06-06 00:57:02.000000000 +0000
> +++ linux-2.6.17-rc6.work/arch/powerpc/kernel/sysfs.c	2006-06-13 21:42:32.000000000 +0000
> @@ -356,6 +356,39 @@ static ssize_t show_physical_id(struct s
>  }
>  static SYSDEV_ATTR(physical_id, 0444, show_physical_id, NULL);
>  
> +#ifdef CONFIG_HCALL_STATS
> +DECLARE_PER_CPU(struct hcall_stats[MAX_HCALL_OPCODES+1], hcall_stats);
> +
> +static ssize_t show_hcall_stats(struct sys_device *dev, char *buf)
> +{
> +	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
> +	struct hcall_stats *hs = per_cpu(hcall_stats, cpu->sysdev.id);
> +	size_t rc = 0;
> +	size_t b_written = 0;
> +	size_t b_remain = PAGE_SIZE;
> +	unsigned long i;
> +
> +	for (i=0; i<MAX_HCALL_OPCODES+1; i++){
> +		if (!hs[i].num_calls)
> +			continue;
> +
> +		b_written = snprintf(buf+rc, b_remain,
> +				"%lu %lu %lu\n",
> +				i<<2, hs[i].num_calls, hs[i].total_time);
> +
> +		if (b_written >= b_remain)
> +			break;	/* end of buffer */
> +
> +		rc += b_written;
> +		b_remain -= b_written;
> +	}
> +
> +	return rc;
> +}
> +

You're violating the "one value per file" rule for sysfs.  Ware the
wrath of Greg KH.

Dave B

[RFC] New hcall mechanism Was: [PATCH 0/3] powerpc: Instrument Hypervisor Calls

[Jimi Xenidis]

Looking at this patch set, it reminds me how IMNSHO the plpar calling  
mechanism in Linux are a little arcane.
When we were writing "toy" OSes for hypervisors we had the following  
assembly:

### NOTE: this code does not accommodate passing args in r11 & r12  
(arg 8 and 9),
### and 'in' could be used to streamline the fetching of r11 & r12  
from the stack where the ABI has placed them.
#define PAPR(in, out, name, func_code)	\
	_GLOBAL(name);	 		\
         /* profiling code here */		\
	std r3,-GPR_WIDTH(r1); 		\
	li r3,func_code; 		\
	HSC;				\
         /* profiling code here */		\
	ld r12,-GPR_WIDTH(r1);		\
	cmpi 0,r12,0;			\
         bne ret	## out;	/* only store regs if r12 != NULL,  
indicating the caller does not care about the return value */ \
	b ret0

ret7:	std r10, 6 * GPR_WIDTH(r12)
ret6:	std r9, 5 * GPR_WIDTH(r12)
ret5:	std r8, 4 * GPR_WIDTH(r12)
ret4:	std r7, 3 * GPR_WIDTH(r12)
ret3:	std r6, 2 * GPR_WIDTH(r12)
ret2:	std r5, 1 * GPR_WIDTH(r12)
ret1:	std r4, 0 * GPR_WIDTH(r12)
	nop
ret0:	blr
	
PAPR(4, 1,papr_enter, H_ENTER)
...

This allowes for the C interface for H_ENTER to be:
   long papr_enter(ulong *slot, ulong flags, ulong hpte_group, ulong  
hpte_v, ulong hpte_r);

making the call:
   ulong slot;
   lapr_rc = papr_enter(&slot, flags, hpte_group, hpte_v, hpte_r);
Rather than:
   ulong slot, dummy0, dummy1;
   lpar_rc = plpar_hcall(H_ENTER, flags, hpte_group, hpte_v, hpte_r,  
&slot, &dummy0, &dummy1);

The latter saving pointers to stack variables on the stack before the  
call.

A mechanism such as this could also make the profiling far simpler  
and efficient as the profiling code get generated by the PAPR() macro  
above.
I is also possible to generate the prototypes from the PAPR()  
statements above.


Comments welcome?
-JX

On Jun 13, 2006, at 11:47 PM, Mike Kravetz wrote:

> This patch series adds instrumentation to Hypervisor calls.  Code and
> ideas were taken from the patch set provided by Christopher Yeoh.
>
> The idea is to put all instrumentation code behind a configuration
> option so that it can easily be added/removed.  The instrumentation
> code is kept to a minimum in the hopes that it's impact to performance
> will not be noticed.  Statistics are made available via files in  
> sysfs.
>
> -- 
> Mike
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-dev

Re: [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers

[Nathan Lynch]

Mike Kravetz wrote:
> +config HCALL_STATS
> +	bool "Hypervisor call instrumentation"
> +	depends on PPC_PSERIES
> +	help
> +	  Adds code to keep track of number of hypervisor calls made and
> +	  the amount of time spent in hypervisor calls.
> +
> +	  This option will add a small amount of overhead to all hypervisor
> +	  calls.

Would be good to say how the stats are made available to userspace
here.


> +DEFINE_PER_CPU(struct hcall_stats[MAX_HCALL_OPCODES+1], hcall_stats);
> +
> +static inline void update_stats(unsigned long opcode, unsigned long t_before)
> +{
> +	unsigned long op_index= opcode >> 2;
> +	struct hcall_stats *hs = &__get_cpu_var(hcall_stats[op_index]);
> +
> +	/* racey, but acceptable for non-critical stats */
> +	hs->total_time += (mfspr(SPRN_PURR) - t_before);
> +	hs->num_calls++;
> +}
> +
> +extern long plpar_hcall_base (unsigned long opcode,
> +                 unsigned long arg1,
> +                 unsigned long arg2,
> +                 unsigned long arg3,
> +                 unsigned long arg4,
> +                 unsigned long *out1,
> +                 unsigned long *out2,
> +                 unsigned long *out3);
> +
> +long plpar_hcall(unsigned long opcode,
> +                 unsigned long arg1,
> +                 unsigned long arg2,
> +                 unsigned long arg3,
> +                 unsigned long arg4,
> +                 unsigned long *out1,
> +                 unsigned long *out2,
> +                 unsigned long *out3)
> +{
> +	long rc;
> +	unsigned long t_before = mfspr(SPRN_PURR);
> +
> +	rc = plpar_hcall_base(opcode, arg1, arg2, arg3, arg4, out1, out2, out3);
> +
> +	update_stats(opcode, t_before);
> +	return rc;
> +}

Without disabling preemption around the mfspr ... update_stats section
in these hcall wrappers, you risk updating the stats on the wrong cpu.


> +struct hcall_stats {
> +	unsigned long	num_calls;
> +	unsigned long	total_time;
> +};

A comment explaining the unit of time used for the total_time field
would be nice.

Re: [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers

[Paul Mackerras]

Nathan Lynch writes:

> Without disabling preemption around the mfspr ... update_stats section
> in these hcall wrappers, you risk updating the stats on the wrong cpu.

I think we are only looking for total counts and times anyway, so it
doesn't really matter which cpu updates the stats, as long as the time
gets accounted on some cpu.  The use of per-cpu counters is just for
better cache behaviour.

Paul.

Re: [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers

[Nathan Lynch]

Paul Mackerras wrote:
> Nathan Lynch writes:
> 
> > Without disabling preemption around the mfspr ... update_stats section
> > in these hcall wrappers, you risk updating the stats on the wrong cpu.
> 
> I think we are only looking for total counts and times anyway, so it
> doesn't really matter which cpu updates the stats, as long as the time
> gets accounted on some cpu.  The use of per-cpu counters is just for
> better cache behaviour.

Makes sense... then perhaps the stats shouldn't be exported in per-cpu
files in sysfs, and the kernel should calculate and report the totals
to userspace in some other form.

Re: [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers

[Mike Kravetz]

On Wed, Jun 14, 2006 at 05:40:40PM -0500, Nathan Lynch wrote:
> Makes sense... then perhaps the stats shouldn't be exported in per-cpu
> files in sysfs, and the kernel should calculate and report the totals
> to userspace in some other form.

I'm really wondering what would be the best way to make these stats
available to userspace.  As mentioned, putting them into sysfs would
violate the one value/one file rule.  The use of /proc is discouraged.
debugfs was mentioned, but I have never used it.  Noticed that debugfs
was enabled in the default config (at least for pseries).  Looks like
that would be the best alternative.  Agree?

-- 
Mike

Re: [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers

[Arnd Bergmann]

On Thursday 15 June 2006 01:52, Mike Kravetz wrote:
> I'm really wondering what would be the best way to make these stats
> available to userspace. =A0As mentioned, putting them into sysfs would
> violate the one value/one file rule. =A0The use of /proc is discouraged.
> debugfs was mentioned, but I have never used it. =A0Noticed that debugfs
> was enabled in the default config (at least for pseries). =A0Looks like
> that would be the best alternative. =A0Agree?

Debugfs sounds good. If you use one file per hcall, it's probably as
easy as

static u64 hcall_stats_get(void *data)
{
	unsigned long index =3D (unsigned long)data;
	return read_hcall_count(index);
}
DEFINE_SIMPLE_ATTRIBUTE(hcall_fops, hcall_stats_get, NULL, "%llu\n");

void hcall_stats_create(void)
{
	unsigned long i;
	struct dentry *dir;

	dir =3D debugfs_create_dir("hcall_stats", NULL);
	for (i=3D0; i <=3D MAX_HCALL_OPCODES; i++) {
		char name[16];
		sprintf(name, "%d", i << 2);
		debugfs_create_file(name, 0444, dir, (void *)i, &hcall_fops);
	}
}

	Arnd <><

Re: [PATCH 0/3] powerpc: Instrument Hypervisor Calls: add sysfs files

[Christopher Yeoh]

At 2006/6/14 09:22-0500  Nathan Lynch writes:
> > +
> > +static SYSDEV_ATTR(hcall_stats, 0666, show_hcall_stats, NULL);
> 
> Mode should be 0444 or 0400, no need to have write permissions.
> 

The original version zeroed all of the counters if you wrote anything
to the file. This was kind of handy when doing test runs.

Chris
-- 
cyeoh@au.ibm.com
IBM OzLabs Linux Development Group
Canberra, Australia

Re: [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers

[Mike Kravetz]

On Thu, Jun 15, 2006 at 01:09:39PM +0200, Arnd Bergmann wrote:
> On Thursday 15 June 2006 01:52, Mike Kravetz wrote:
> > I'm really wondering what would be the best way to make these stats
> > available to userspace.  As mentioned, putting them into sysfs would
> > violate the one value/one file rule.  The use of /proc is discouraged.
> > debugfs was mentioned, but I have never used it.  Noticed that debugfs
> > was enabled in the default config (at least for pseries).  Looks like
> > that would be the best alternative.  Agree?
> 
> Debugfs sounds good. If you use one file per hcall, it's probably as
> easy as

But does debugfs have the same one value/one file rule?  Thought I could
dump all the data in a single debugfs file.

-- 
Mike

Re: [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers

[Arnd Bergmann]

On Thursday 15 June 2006 16:58, Mike Kravetz wrote:
> But does debugfs have the same one value/one file rule? =A0Thought I could
> dump all the data in a single debugfs file.

Sure, you could. It just makes it a little more complicated. You probably
need to use a seq_file then.

	Arnd <><

Re: [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers

[Mike Kravetz]

On Thu, Jun 15, 2006 at 08:33:55AM +1000, Paul Mackerras wrote:
> Nathan Lynch writes:
> 
> > Without disabling preemption around the mfspr ... update_stats section
> > in these hcall wrappers, you risk updating the stats on the wrong cpu.
> 
> I think we are only looking for total counts and times anyway, so it
> doesn't really matter which cpu updates the stats, as long as the time
> gets accounted on some cpu.  The use of per-cpu counters is just for
> better cache behaviour.

Thought about this a little more.

We do an mfspr to get a 'timestamp' before the actual hcall.  Then, make
the hcall and do another mfspr after.  Isn't it possible to be preempted
and perform the mfspr's on separate CPUs?  Worse yet, wouldn't this possibly
add 'time preempted' to the hcall time?.  Do we have the same (skewed time)
issue with interrupts?

Thinking that enable/disable around the call might be worth the overhead.
But, disabling interrupts would not be worth it.

-- 
Mike