Octavian Purdila wrote:
On Thursday 04 February 2010 19:41:10 you wrote:
From: Octavian Purdila <opurdila@xxxxxxxxxxx>
Date: Thu, 4 Feb 2010 14:44:01 +0200
My concern is that we can have multiple applications that require a
fixed port and if those ports are significantly apart we will
decrease the port range available for connect. And that will hurt
the rate of which new connections can be opened.
I'm already uneasy about adding the simple check every time
we loop around in the bind port allocator.
Adding an LSM hook to this spot? I absolutely refuse to allow
that, it will completely kill bind performance.
I think Tetsuo was proposing the LSM hook, so I'll leave him the daunting task
of convincing you of the benefit of that :) - I have no opinion on this due to
massive lack of knowledge.
I was just proposing to use a discrete set of ports instead of a range. The
check in the current patch:
int inet_is_reserved_local_port(int port)
{
int min, max;
inet_get_local_reserved_ports(&min, &max);
if (min && max)
return (port >= min && port <= max);
return 0;
}
would become:
int inet_is_reserved_local_port(int port)
{
if (test_bit(port, reserved_ports))
return 1;
return 0;
}
In theory it might be slower because of the reserved_ports bitmap will have a
larger memory footprint than just a min/max, especially with random port
allocation. But is this an issue in practice?
Again, using bitmap algorithm is not a problem and it's better, the
problem is sysctl interface, how would you plan to interact with users
via sysctl/proc if you use bitmap to handle this? I would like to hear
more details about this.
Thanks!
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