Re: Performance Stats: Kernel patch
From: Maxim Uvarov
Date: Wed Apr 04 2007 - 12:52:28 EST
Hello Eric,
I changed patch according to your comments.
Could you please take a look at it?
Eric Dumazet wrote:
On Wed, 04 Apr 2007 17:15:43 +0400
Maxim Uvarov <muvarov@xxxxxxxxxxxxx> wrote:
--- linux-2.6.18.orig/arch/i386/kernel/entry.S
+++ linux-2.6.18/arch/i386/kernel/entry.S
@@ -394,6 +394,9 @@ syscall_exit:
cli # make sure we don't miss an
interrupt
# setting need_resched or sigpending
# between sampling and the iret
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ call inc_syscallcnt # Increment syscalls counter
current->sysc_cnt
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
Please dont call a function to do one increment !
Yes, you are right. I have changed it.
You are touching one of the most critical part of the kernel...
Also, dont do this while interrupts are masked, this is not necessary.
Maybe better to place sysc_cnt in 'struct thread_info' because %ebp point to it.
Also you missed the fact that syscalls on i386 can use sysenter (around line 343)
TRACE_IRQS_OFF
movl TI_flags(%ebp), %ecx
testw $_TIF_ALLWORK_MASK, %cx # current->work
I rewrote this patch for x86. And I have question. Should /proc/PID/status
be used for these counters and this option be selectable or it will
better to
create another file in /proc/PID/ directory?
I will include syscall counters for other arches later.
P.S.
Jesper Juhl, thank you.
Best regards,
Maxim.
Signed-off-by: Max Uvarov <muvarov@xxxxxxxxxxxxx>
Description:
Patch adds Process Performance Statistics.
arch/i386/kernel/asm-offsets.c | 3 +++
arch/i386/kernel/entry.S | 6 ++++++
fs/proc/array.c | 14 ++++++++++++++
include/asm/thread_info.h | 3 +++
kernel/fork.c | 3 +++
lib/Kconfig.debug | 16 ++++++++++++++++
6 files changed, 45 insertions(+)
Index: linux-2.6.18/fs/proc/array.c
===================================================================
--- linux-2.6.18.orig/fs/proc/array.c
+++ linux-2.6.18/fs/proc/array.c
@@ -295,6 +295,20 @@ 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",
cap_t(p->thread_info->sysc_cnt));
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
+
+ return buffer + sprintf(buffer, "Nvcsw:\t%lu\n"
+ "Nivcsw:\t%lu\n",
+ cap_t(p->nvcsw),
+ cap_t(p->nivcsw));
+}
+#endif /* CONFIG_THREAD_PERF_STAT */
+
#define get_blocked_on(t) (-1)
static char *show_blocked_on(struct task_struct *task, char *buffer)
Index: linux-2.6.18/arch/i386/kernel/entry.S
===================================================================
--- linux-2.6.18.orig/arch/i386/kernel/entry.S
+++ linux-2.6.18/arch/i386/kernel/entry.S
@@ -334,6 +334,9 @@ sysenter_past_esp:
jae syscall_badsys
call *sys_call_table(,%eax,4)
movl %eax,EAX(%esp)
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ incl TI_sysc_cnt(%ebp) # Increment syscalls counter
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
#ifdef CONFIG_MICROSTATE
call msa_end_syscall
#endif
@@ -388,6 +391,9 @@ syscall_call:
call *sys_call_table(,%eax,4)
movl %eax,EAX(%esp) # store the return value
syscall_exit:
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ incl TI_sysc_cnt(%ebp) # Increment syscalls counter
current->sysc_cnt
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
#ifdef CONFIG_MICROSTATE
call msa_end_syscall
#endif
Index: linux-2.6.18/lib/Kconfig.debug
===================================================================
--- linux-2.6.18.orig/lib/Kconfig.debug
+++ linux-2.6.18/lib/Kconfig.debug
@@ -539,4 +539,20 @@ config RCU_TORTURE_TEST
Say M if you want the RCU torture tests to build as a module.
Say N if you are unsure.
+config THREAD_PERF_STAT
+ bool "Per-process (thread) performance statistics"
+ depends on X86
+ 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
+ help
+ This option adds a syscall counter to /proc/PID/status.
+
source "lib/Kconfig.kgdb"
Index: linux-2.6.18/include/asm/thread_info.h
===================================================================
--- linux-2.6.18.orig/include/asm/thread_info.h
+++ linux-2.6.18/include/asm/thread_info.h
@@ -44,6 +44,9 @@ struct thread_info {
of nested (IRQ) stacks
*/
__u8 supervisor_stack[0];
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ unsigned long sysc_cnt; /* Syscall counter */
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
};
#else /* !__ASSEMBLY__ */
Index: linux-2.6.18/kernel/fork.c
===================================================================
--- linux-2.6.18.orig/kernel/fork.c
+++ linux-2.6.18/kernel/fork.c
@@ -1079,6 +1079,9 @@ static struct task_struct *copy_process(
p->wchar = 0; /* I/O counter: bytes written */
p->syscr = 0; /* I/O counter: read syscalls */
p->syscw = 0; /* I/O counter: write syscalls */
+#ifdef CONFIG_THREAD_PERF_STAT_SYSC
+ p->thread_info->sysc_cnt = 0; /* Syscall counter: total
numbers of syscalls */
+#endif /* CONFIG_THREAD_PERF_STAT_SYSC */
acct_clear_integrals(p);
p->it_virt_expires = cputime_zero;
Index: linux-2.6.18/arch/i386/kernel/asm-offsets.c
===================================================================
--- linux-2.6.18.orig/arch/i386/kernel/asm-offsets.c
+++ linux-2.6.18/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();
-
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