Re: Performance Stats: Kernel patch

From: Maxim Uvarov
Date: Wed Apr 11 2007 - 11:53:13 EST

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In reply to: Maxim Uvarov: "Re: Performance Stats: Kernel patch"
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Eric Dumazet wrote:

>Please check kernel/sys.c:k_getrusage() to see how getrusage() has to sum *lot* of individual fields to get precise process numbers (even counting stats for dead threads)

Thanks for helping me and for this link. But it is not enough clear for me what do you mean at this time. Inside of patch I am using 2 default counters
task_struct->nivcsw and task_struct->nvcsw. And also one new syscall counter. And there is only one way to increment this counter, it is from entry.S.

If you are speaking about locks, in my point of view, they are not needed in this code. Because increment syscall counter is atomic for X86 (just one assembly instruction) and in case with PPC (3 instructions) there 1) nothing wrong will not happen in any case 2) only own thread can increase it's syscall counter. So here should be not any race conditions.

I've tested this patch on x86,x86_64,and ppc_32. And I should work now with ppc_64 (I didn't check).
And also updated description.

Best regards,
Maxim Uvarov.
Patch adds Process Performance Statistics.
It make available to the user the following
thread performance statistics:
* Involuntary Context Switches (task_struct->nivcsw)
* Voluntary Context Switches (task_struct->nvcsw)
* Number of system calls (added new counter
thread_info->sysc_cnt)

Statistics information is available from
/proc/PID/status

This data is useful for detecting hyperactivity
patterns between processes.

Signed-off-by: Maxim Uvarov muvarov@xxxxxxxxxxxxx

arch/i386/kernel/asm-offsets.c | 3 +++
arch/i386/kernel/entry.S | 3 +++
arch/powerpc/kernel/asm-offsets.c | 4 ++++
arch/powerpc/kernel/entry_32.S | 5 +++++
arch/powerpc/kernel/entry_64.S | 5 +++++
arch/x86_64/kernel/asm-offsets.c | 3 +++
arch/x86_64/kernel/entry.S | 3 +++
fs/proc/array.c | 17 +++++++++++++++++
include/asm-i386/thread_info.h | 5 +++--
include/asm-powerpc/thread_info.h | 3 +++
include/asm-x86_64/thread_info.h | 4 +++-
kernel/fork.c | 4 ++++
lib/Kconfig.debug | 15 +++++++++++++++
13 files changed, 71 insertions(+), 3 deletions(-)

Index: linux-2.6.21-rc5/fs/proc/array.c
===================================================================
--- linux-2.6.21-rc5.orig/fs/proc/array.c
+++ linux-2.6.21-rc5/fs/proc/array.c
@@ -291,6 +291,20 @@ static inline char *task_cap(struct task
cap_t(p->cap_effective));
}

+#ifdef CONFIG_THREAD_PERF_STAT
+static inline char *task_perf(struct task_struct *p, char *buffer)
+{
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ buffer += sprintf(buffer, "Syscalls:\t%lu\n", p->thread_info->sysc_cnt);
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
+
+ return buffer + sprintf(buffer, "Nvcsw:\t%lu\n"
+ "Nivcsw:\t%lu\n",
+ p->nvcsw,
+ p->nivcsw);
+}
+#endif /* CONFIG_THREAD_PERF_STAT */
+
int proc_pid_status(struct task_struct *task, char * buffer)
{
char * orig = buffer;
@@ -309,6 +323,9 @@ int proc_pid_status(struct task_struct *
#if defined(CONFIG_S390)
buffer = task_show_regs(task, buffer);
#endif
+#ifdef CONFIG_THREAD_PERF_STAT
+ buffer = task_perf(task, buffer);
+#endif /* CONFIG_THREAD_PERF_STAT */
return buffer - orig;
}

Index: linux-2.6.21-rc5/kernel/fork.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/fork.c
+++ linux-2.6.21-rc5/kernel/fork.c
@@ -1044,6 +1044,10 @@ static struct task_struct *copy_process(
p->syscr = 0; /* I/O counter: read syscalls */
p->syscw = 0; /* I/O counter: write syscalls */
#endif
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ p->thread_info->sysc_cnt = 0; /* Syscall counter: total numbers of syscalls */
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
+
task_io_accounting_init(p);
acct_clear_integrals(p);

Index: linux-2.6.21-rc5/lib/Kconfig.debug
===================================================================
--- linux-2.6.21-rc5.orig/lib/Kconfig.debug
+++ linux-2.6.21-rc5/lib/Kconfig.debug
@@ -446,3 +446,18 @@ config FAULT_INJECTION_STACKTRACE_FILTER
select FRAME_POINTER
help
Provide stacktrace filter for fault-injection capabilities
+
+config THREAD_PERF_STAT
+ bool "Per-process (thread) performance statistics"
+ help
+ Make available to the user the following per-process (thread) performance statistics:
+ * Number of involuntary context switches
+ * Number of voluntary context switches
+ * Number of system calls (optional)
+ This information is available via /proc/PID/status.
+
+config THREAD_PERF_STAT_SYSC
+ bool "Enable syscall counter"
+ depends on THREAD_PERF_STAT && (X86 || PPC)
+ help
+ This option adds a syscall counter to /proc/PID/status.
Index: linux-2.6.21-rc5/arch/i386/kernel/entry.S
===================================================================
--- linux-2.6.21-rc5.orig/arch/i386/kernel/entry.S
+++ linux-2.6.21-rc5/arch/i386/kernel/entry.S
@@ -334,6 +334,9 @@ sysenter_past_esp:
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
GET_THREAD_INFO(%ebp)
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ incl TI_sysc_cnt(%ebp) # Increment syscalls counter
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */

/* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */
testw $(_TIF_SYSCALL_EMU|_TIF_SYSCALL_TRACE|_TIF_SECCOMP|_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
Index: linux-2.6.21-rc5/arch/i386/kernel/asm-offsets.c
===================================================================
--- linux-2.6.21-rc5.orig/arch/i386/kernel/asm-offsets.c
+++ linux-2.6.21-rc5/arch/i386/kernel/asm-offsets.c
@@ -56,6 +56,9 @@ void foo(void)
OFFSET(TI_addr_limit, thread_info, addr_limit);
OFFSET(TI_restart_block, thread_info, restart_block);
OFFSET(TI_sysenter_return, thread_info, sysenter_return);
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ OFFSET(TI_sysc_cnt, thread_info, sysc_cnt);
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
BLANK();

OFFSET(GDS_size, Xgt_desc_struct, size);
Index: linux-2.6.21-rc5/include/asm-i386/thread_info.h
===================================================================
--- linux-2.6.21-rc5.orig/include/asm-i386/thread_info.h
+++ linux-2.6.21-rc5/include/asm-i386/thread_info.h
@@ -31,8 +31,9 @@ struct thread_info {
unsigned long status; /* thread-synchronous flags */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
-
-
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ unsigned long sysc_cnt; /* Syscall counter */
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
0-0xFFFFFFFF for kernel-thread
Index: linux-2.6.21-rc5/arch/powerpc/kernel/asm-offsets.c
===================================================================
--- linux-2.6.21-rc5.orig/arch/powerpc/kernel/asm-offsets.c
+++ linux-2.6.21-rc5/arch/powerpc/kernel/asm-offsets.c
@@ -94,6 +94,10 @@ int main(void)
DEFINE(TI_LOCAL_FLAGS, offsetof(struct thread_info, local_flags));
DEFINE(TI_PREEMPT, offsetof(struct thread_info, preempt_count));
DEFINE(TI_TASK, offsetof(struct thread_info, task));
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ DEFINE(TI_SYSC_CNT, offsetof(struct thread_info, sysc_cnt));
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
+
#ifdef CONFIG_PPC32
DEFINE(TI_EXECDOMAIN, offsetof(struct thread_info, exec_domain));
DEFINE(TI_CPU, offsetof(struct thread_info, cpu));
Index: linux-2.6.21-rc5/arch/powerpc/kernel/entry_32.S
===================================================================
--- linux-2.6.21-rc5.orig/arch/powerpc/kernel/entry_32.S
+++ linux-2.6.21-rc5/arch/powerpc/kernel/entry_32.S
@@ -202,6 +202,11 @@ _GLOBAL(DoSyscall)
bl do_show_syscall
#endif /* SHOW_SYSCALLS */
rlwinm r10,r1,0,0,(31-THREAD_SHIFT) /* current_thread_info() */
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ lwz r11,TI_SYSC_CNT(r10)
+ addi r11,r11,1
+ stw r11,TI_SYSC_CNT(r10)
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
lwz r11,TI_FLAGS(r10)
andi. r11,r11,_TIF_SYSCALL_T_OR_A
bne- syscall_dotrace
Index: linux-2.6.21-rc5/arch/powerpc/kernel/entry_64.S
===================================================================
--- linux-2.6.21-rc5.orig/arch/powerpc/kernel/entry_64.S
+++ linux-2.6.21-rc5/arch/powerpc/kernel/entry_64.S
@@ -115,6 +115,11 @@ END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISER
addi r9,r1,STACK_FRAME_OVERHEAD
#endif
clrrdi r11,r1,THREAD_SHIFT
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ ld r10,TI_SYSC_CNT(r11)
+ addi r10,r10,1
+ std r10,TI_SYSC_CNT(r11)
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
ld r10,TI_FLAGS(r11)
andi. r11,r10,_TIF_SYSCALL_T_OR_A
bne- syscall_dotrace
Index: linux-2.6.21-rc5/arch/x86_64/kernel/asm-offsets.c
===================================================================
--- linux-2.6.21-rc5.orig/arch/x86_64/kernel/asm-offsets.c
+++ linux-2.6.21-rc5/arch/x86_64/kernel/asm-offsets.c
@@ -35,6 +35,9 @@ int main(void)
ENTRY(addr_limit);
ENTRY(preempt_count);
ENTRY(status);
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ ENTRY(sysc_cnt);
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
BLANK();
#undef ENTRY
#define ENTRY(entry) DEFINE(pda_ ## entry, offsetof(struct x8664_pda, entry))
Index: linux-2.6.21-rc5/arch/x86_64/kernel/entry.S
===================================================================
--- linux-2.6.21-rc5.orig/arch/x86_64/kernel/entry.S
+++ linux-2.6.21-rc5/arch/x86_64/kernel/entry.S
@@ -229,6 +229,9 @@ ENTRY(system_call)
movq %rcx,RIP-ARGOFFSET(%rsp)
CFI_REL_OFFSET rip,RIP-ARGOFFSET
GET_THREAD_INFO(%rcx)
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ addq $1, threadinfo_sysc_cnt(%rcx) # Increment syscalls counter
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP),threadinfo_flags(%rcx)
jnz tracesys
cmpq $__NR_syscall_max,%rax
Index: linux-2.6.21-rc5/include/asm-powerpc/thread_info.h
===================================================================
--- linux-2.6.21-rc5.orig/include/asm-powerpc/thread_info.h
+++ linux-2.6.21-rc5/include/asm-powerpc/thread_info.h
@@ -35,6 +35,9 @@ struct thread_info {
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable,
<0 => BUG */
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ unsigned long sysc_cnt; /* Syscall counter */
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
struct restart_block restart_block;
unsigned long local_flags; /* private flags for thread */

Index: linux-2.6.21-rc5/include/asm-x86_64/thread_info.h
===================================================================
--- linux-2.6.21-rc5.orig/include/asm-x86_64/thread_info.h
+++ linux-2.6.21-rc5/include/asm-x86_64/thread_info.h
@@ -30,7 +30,9 @@ struct thread_info {
__u32 status; /* thread synchronous flags */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
-
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ unsigned long sysc_cnt; /* Syscall counter */
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
mm_segment_t addr_limit;
struct restart_block restart_block;
};

Next message: Jeff Garzik: "Re: [PATCH 2.6.21 1/3] cxgb3 - avoid deadlock with mac watchdog"
Previous message: John Stoffel: "Re: I give up"
In reply to: Maxim Uvarov: "Re: Performance Stats: Kernel patch"
Next in thread: Eric Dumazet: "Re: Performance Stats: Kernel patch"
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