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

[Guillaume Thouvenin <guillaume.thouvenin@xxxxxxxx>]

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;
        }