netdev - Re: [net-next PATCH v4 0/3] net: reserve ports for applications using fixed port

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Message-ID: <m17hqd583i.fsf@fess.ebiederm.org>
Date:	Tue, 16 Feb 2010 10:49:37 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Octavian Purdila <opurdila@...acom.com>
Cc:	David Miller <davem@...emloft.net>,
	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	Linux Kernel Developers <linux-kernel@...r.kernel.org>,
	Amerigo Wang <amwang@...hat.com>
Subject: Re: [net-next PATCH v4 0/3] net: reserve ports for applications using fixed port

Octavian Purdila <opurdila@...acom.com> writes:

> Hi Eric, thanks for going over this.
>
> The use case (large bitmaps/lists) is different enough from what we have today 
> (small bitmaps) and that is why I think that we need this new interface. 
>
> If I get bitmap_parse_user correctly, for a 64k bitmap it expects a 2K comma 
> separated values. That is not the most intuitively way for the user to set a 
> list of ports he wants to reserve. 

In this case I expect an interface of comma separated ranges would be
ideal.  Typically compact, and modifiable by writing the new value to
the file.

I think the default value would be something like 32768-61000.

> Using 64K files has the same practical issues (the user would have to cat all 
> 64K files to determine which ports are reserved) plus it has issues caused by 
> the large number of files: significant memory overhead and also significant time 
> for registering those files.

"grep -l 1 *" isn't particularly difficult, and it would be one sysctl registration
call.  It is true that the sysctl memory footprint would be a pain in that case.

Eric




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