Hello,
I want to implement what I called "bank" of processus. The idea is to provide
a mechanism that allows me to group chosen process together. This "bank" must
have some properties like:
o If a process belongs to a bank, its children belong to the same bank
o A process can be placed in several different banks
o When the user adds a process to an non-existent bank, the container
must automatically be created
o When the last process of a bank exits, informations about all processes
that belonged to the bank must be stored (maybe in a file) and the
container must be destroyed
To do that, I use a double linked list provides by the kernel
(include/linux/list.h) and I do the following thing:
BANK 1 BANK 2
----------- -------- --------
| bank head |<----->| bank_s |<------>| bank_s |<------>...
----------- | | | |
-------- --------
^ ^
| |
-------- | | --------
| data_s |<--- --->| data_s |
process <--| | | |
-------- --------
| |
| |
... <-- data_s <-- --> data_s -> ...
To manipulate those structures I created a system call that is the interface
between the kernel and the user. I wrote those things inside the kernel because
the structure data_s holds information about process that is available inside
the kernel. The system call must be able to create/delete a "bank" and it must
be able to add/remove a process in a "bank". So, I added an opcode in the list
of system call arguments. I also want to provide a mechanism that will display
information in the /proc filesystem. for example, let B1={P1, P2} be a bank
with two process, I will display something like:
# ls /proc/banks
1
# cat /proc/banks/1
1 2
In this implementation, the main problem is if I want to know in which bank
a process is present using the process ID, I must go through the list of all
banks. To improve that, I want to add a field in the task_struct in order to
give myself an entry on a list of banks.
Question is:
What do you think of this implementation? I mean is it possible to do the
same thing with less modifications inside the kernel. For example, is it
possible to do it whitout adding a new sytem call or is it possible to do that
using the /proc interface directly? In the case where it is possible, will it
be more efficient knowing that the aim is to do accounting (like BSD-accounting
but not only for one process at the same time).
I pasted at the end of this mail a patch that shows what I've already done.
Of course it's just a skeleton of the system call but before going further, I
will be interested to have some opinions concerning the project and its
implementation. You will find more informations at
http://elsa.sourceforge.net
Thank you for your comments
Guillaume Thouvenin
-----B<------
diff -uprN linux-2.6.5/arch/i386/kernel/entry.S
linux-2.6.5-elsa/arch/i386/kernel/entry.S
--- linux-2.6.5/arch/i386/kernel/entry.S 2004-04-04 05:36:52.000000000 +0200
+++ linux-2.6.5-elsa/arch/i386/kernel/entry.S 2004-04-06 10:28:29.000000000 +0200
@@ -882,5 +882,6 @@ ENTRY(sys_call_table)
.long sys_utimes
.long sys_fadvise64_64
.long sys_ni_syscall /* sys_vserver */
+ .long sys_elsa
syscall_table_size=(.-sys_call_table)
diff -uprN linux-2.6.5/include/linux/elsa.h linux-2.6.5-elsa/include/linux/elsa.h
--- linux-2.6.5/include/linux/elsa.h 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.5-elsa/include/linux/elsa.h 2004-04-06 16:26:16.000000000 +0200
@@ -0,0 +1,87 @@
+/*
+ * include/linux/elsa.h
+ *
+ * Copyright (C) 2004 Guillaume Thouvenin
+ *
+ * ELSA - Enhanced Linux System Accounting
+ */
+
+#ifndef __LINUX_ELSA_H
+#define __LINUX_ELSA_H
+
+#include <linux/list.h>
+#include <linux/sched.h>
+
+/*
+ * sys_elsa() interface.
+ *
+ * int sys_elsa(int opcode,
+ * unsigned int arg0,
+ * unsigned int arg1,
+ * unsigned int arg2)
+ *
+ *
+ */
+
+enum elsa_opcode {
+ /*
+ * Initialize the head of the list of banks.
+ * ARG0 is a pointer to the head of the list of banks. The list must
+ * be empty when called. It enables Enhanced Linux System Accounting.
+ * ARG1 and ARG2 are not used
+ */
+ BANK_ON,
+ /*
+ * Currently, it does nothing.
+ */
+ BANK_OFF,
+ /*
+ * Allocate a new bank and return the identifier of the new created
+ * bank. If it fails, it returns 0. i
+ * ARG0 is a pointer to the head of the list of banks.
+ * ARG1, ARG2 are not used.
+ */
+ BANK_ALLOC,
+ /*
+ * Free previously allocated bank.
+ * ARG0 is a pointer to the head of the list of banks,
+ * ARG1 is the identifier of the bank,
+ * ARG2 is not used.
+ */
+ BANK_FREE,
+ /*
+ * Add a process to a given bank.
+ * ARG0 is a pointer to the head of the list of banks,
+ * ARG1 is the identifier of the bank,
+ * ARG2 is the pid of the process to add.
+ */
+ BANK_ADD,
+ /*
+ * Remove a process to a given bank.
+ * ARG0 is a pointer to the head of the list of banks,
+ * ARG1 is the identifier of the bank,
+ * ARG2 is the pid of the process to add.
+ */
+ BANK_REMOVE
+};
+
+struct bank_root_s {
+ int next_id; /* next available bank identifier */
+ struct list_head head; /* head of the list of bank */
+};
+
+struct elsa_bank_s {
+ int id; /* the bank identifier */
+ struct list_head banks; /* list of available banks */
+ struct list_head head; /* head of the list of datas in the
+ bank */
+};
+
+struct elsa_data_s {
+ struct task_struct *process; /* the process information */
+ struct list_head datas; /* link between datas in a bank */
+ struct list_head banks; /* used by the processus to link banks
+ that contains it */
+};
+
+#endif /* !(__LINUX_ELSA_H) */
diff -uprN linux-2.6.5/include/linux/syscalls.h
linux-2.6.5-elsa/include/linux/syscalls.h
--- linux-2.6.5/include/linux/syscalls.h 2004-04-04 05:38:26.000000000 +0200
+++ linux-2.6.5-elsa/include/linux/syscalls.h 2004-04-06 10:35:12.000000000 +0200
@@ -471,6 +471,8 @@ asmlinkage long sys_nfsservctl(int cmd,
void __user *res);
asmlinkage long sys_syslog(int type, char __user *buf, int len);
asmlinkage long sys_uselib(const char __user *library);
+asmlinkage long sys_elsa(int opcode, unsigned int arg0, unsigned int arg1,
+ unsigned int arg2);
asmlinkage long sys_ni_syscall(void);
#endif
diff -uprN linux-2.6.5/init/Kconfig linux-2.6.5-elsa/init/Kconfig
--- linux-2.6.5/init/Kconfig 2004-04-04 05:37:44.000000000 +0200
+++ linux-2.6.5-elsa/init/Kconfig 2004-04-06 09:26:07.000000000 +0200
@@ -104,6 +104,12 @@ config BSD_PROCESS_ACCT
up to the user level program to do useful things with this
information. This is generally a good idea, so say Y.
+config ELSA
+ bool "Enhanced Linux System Accounting"
+ default n
+ ---help---
+ Not available
+
config SYSCTL
bool "Sysctl support"
---help---
diff -uprN linux-2.6.5/kernel/elsa.c linux-2.6.5-elsa/kernel/elsa.c
--- linux-2.6.5/kernel/elsa.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.5-elsa/kernel/elsa.c 2004-04-06 10:34:07.000000000 +0200
@@ -0,0 +1,53 @@
+/*
+ * linux/kernel/elsa.c
+ *
+ * ELSA - Enhanced Linux System Accounting
+ *
+ * Author: Guillaume Thouvenin <guillaume.thouvenin@bull.net>
+ *
+ * This file implements Enhanced Linux System Accounting. It
+ * provides structure and functions to maniupulate "BANK".
+ * They are containers that store a set of processus. It is
+ * to user to manage them using elsa_acct() system call.
+ * When a "BANK" is empty it is destroy and accounting infor-
+ * mations are stored in a file. Informations are about
+ * all processus contained in a "BANK"
+ *
+ * (C) Copyright 2004 Guillaume Thouvenin
+ *
+ */
+
+#include <linux/slab.h>
+#include <linux/mm.h>
+
+#include <linux/elsa.h>
+
+/**
+ * sys_elsa - This is the system call
+ * @opcode
+ *
+ */
+asmlinkage long sys_elsa(int opcode, unsigned int arg0, unsigned int arg1,
unsigned int arg2)
+{
+ int err = 0;
+
+ switch(opcode) {
+ case BANK_ALLOC:
+ break;
+
+ case BANK_FREE:
+ break;
+
+ case BANK_ADD:
+ break;
+
+ case BANK_REMOVE:
+ break;
+
+ default:
+ err = -EINVAL;
+ break;
+ };
+
+ return err;
+}
diff -uprN linux-2.6.5/kernel/Makefile linux-2.6.5-elsa/kernel/Makefile
--- linux-2.6.5/kernel/Makefile 2004-04-04 05:36:26.000000000 +0200
+++ linux-2.6.5-elsa/kernel/Makefile 2004-04-06 09:15:12.000000000 +0200
@@ -21,6 +21,7 @@ obj-$(CONFIG_COMPAT) += compat.o
obj-$(CONFIG_IKCONFIG) += configs.o
obj-$(CONFIG_IKCONFIG_PROC) += configs.o
obj-$(CONFIG_STOP_MACHINE) += stop_machine.o
+obj-$(CONFIG_ELSA) += elsa.o
ifneq ($(CONFIG_IA64),y)
# According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
diff -uprN linux-2.6.5/Makefile linux-2.6.5-elsa/Makefile
--- linux-2.6.5/Makefile 2004-04-04 05:37:36.000000000 +0200
+++ linux-2.6.5-elsa/Makefile 2004-04-06 09:28:26.000000000 +0200
@@ -1,7 +1,7 @@
VERSION = 2
PATCHLEVEL = 6
SUBLEVEL = 5
-EXTRAVERSION =
+EXTRAVERSION = -elsa
NAME=Zonked Quokka
# *DOCUMENTATION*
--
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