From mboxrd@z Thu Jan 1 00:00:00 1970 From: Octavian Purdila Subject: Re: [RFC Patch] net: reserve ports for applications using fixed port numbers Date: Thu, 4 Feb 2010 20:15:51 +0200 Message-ID: <201002042015.51092.opurdila@ixiacom.com> References: <201002031312.48531.opurdila@ixiacom.com> <201002041444.01897.opurdila@ixiacom.com> <20100204.094110.64247447.davem@davemloft.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: amwang-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, eric.dumazet-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, nhorman-2XuSBdqkA4R54TAoqtyWWQ@public.gmane.org, linux-sctp-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: David Miller Return-path: In-Reply-To: <20100204.094110.64247447.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org On Thursday 04 February 2010 19:41:10 you wrote: > From: Octavian Purdila > 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? -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html