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Re: [Help-gnunet] severe performance problems

From: Milan
Subject: Re: [Help-gnunet] severe performance problems
Date: Sun, 18 Sep 2005 11:47:13 +0200
User-agent: Mozilla Thunderbird 1.0.2 (X11/20050602)

Christian Grothoff a écrit :
Ok, let me summarize:

a) you're using a 200 Mhz CPU.  This is sufficient, but barely above the 100
    Mhz minimum requirements.
b) you're experiencing high CPU utilization, but can't tell which process is
    the cause (gnunetd does not show up in top)
c) you're using an encrypted partition to store the GNUnet data

Well, c) causes the kernel (!) to perform encryption/decryption on any IO operation. That's where your CPU is going, and since the kernel has no PID, this is also why it does not show up for any process in b). Also, c) is a bad idea -- GNUnet already (!) encrypts all of the data that is being stored in the database, encrypting it again gives you very little additional security. Worse, it seems to me that it kills your CPU (at the IO-rate that GNUnet has -- remember, on many machines GNUnet can be IO-bound; on yours it is likely CPU bound to start with, and by putting encryption on the disk you make it worse).
Well, I agree with you : encrypted partition is really a bad thing for GNUnet. But I've never been able to see gnuentd's CPU usage. top -p <gnunetd pid> shows that gnunetd CPU usage is always 0.0%, even if some hidden process uses about 100 %. So if David doesn't see anything, it's not only because of his encrypted partition.


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