Re: [Lse-tech] Re: A common layer for Accounting packages

Guillaume Thouvenin
2005-03-01T13:54:38Z

On Tue, 2005-03-01 at 22:38 +0900, Kaigai Kohei wrote:
> > I tested without user space listeners and the cost is negligible. I will
> > test with a user space listeners and see the results. I'm going to run
> > the test this week after improving the mechanism that switch on/off the
> > sending of the message.
>
> I'm also trying to mesure the process-creation/destruction performance on following three environment.
> Archtechture: i686 / Distribution: Fedora Core 3
> * Kernel Preemption is DISABLE
> * SMP kernel but UP-machine / Not Hyper Threading
> [1] 2.6.11-rc4-mm1 normal
> [2] 2.6.11-rc4-mm1 with PAGG based Process Accounting Module
> [3] 2.6.11-rc4-mm1 with fork-connector notification (it's enabled)
>
> When 367th-fork() was called after fork-connector notification, kernel was locked up.
> (User-Space-Listener has been also run until 366th-fork() notification was received)

I don't see this limit on my computer. I'm currently running the lmbench
with a new fork connector patch (one that enable/disable fork connector)
on an SMP computer. I will send results and the new patch tomorrow
because the test takes a while...

I'm using a small patch provided by Evgeniy and not included in the
2.6.11-rc4-mm1 tree.

Best regards,
Guillaume

--- orig/connector.c
+++ mod/connector.c
@@ -168,12 +168,11 @@
group = NETLINK_CB((skb)).groups;
msg = (struct cn_msg *)NLMSG_DATA(nlh);

- if (msg->len != nlh->nlmsg_len - sizeof(*msg) - sizeof(*nlh)) {
+ if (NLMSG_SPACE(msg->len + sizeof(*msg)) != nlh->nlmsg_len) {
printk(KERN_ERR "skb does not have enough length: "
- "requested msg->len=%u[%u], nlh->nlmsg_len=%u[%u], skb->len=%u[must be %u].\n",
- msg->len, NLMSG_SPACE(msg->len),
- nlh->nlmsg_len, nlh->nlmsg_len - sizeof(*nlh),
- skb->len, msg->len + sizeof(*msg));
+ "requested msg->len=%u[%u], nlh->nlmsg_len=%u, skb->len=%u.\n",
+ msg->len, NLMSG_SPACE(msg->len + sizeof(*msg)),
+ nlh->nlmsg_len, skb->len);
kfree_skb(skb);
return -EINVAL;
}