On Sun, Feb 20, 2011 at 06:27:02PM +0100, Martin Koegler wrote: > I did some profiling: > > With TLS, the vncviewer hot spots are: > * ~23% in libgcrypt > * ~14% in the jpeg code > * ~14% again in the jpeg code > > With TLS, the Xvnc hot spots are: > * 17.4% in zlib > * 14.3% libcrypt > * 13% rfb::ComparingUpdateTracker::compareRect > * 12% in the jpeg code
gnutls itself is not performance relevant - the noticeable overhead of using TLS is computing SHA1 hashes as well as AES de-/encryption in libgcrypt. The client spends: * 15% AES decryption * 4.6% SHA1 [for comparison: ~30% in the jpeg code] The server spends: * 9.3% AES encryption * 3.2% SHA1 for comparison: * 25% in the jpeg code * 14% zlib [not TLS related] * 10% ComparingUpdateTracker::compareRect * 10% memcpy [a lot of calls caused by ComparingUpdateTracker::compareRect] Comparing SSH Tunneling with TLS, SSH Tunneling is probably faster because: * OpenSSL has (better) optimized algorithmns then libgcrypt: AES/SHA1 implementations in libgcrypt are in C. * Xvnc is single threaded: SSH tunneling moves the encryption to a second process allowing Xvnc doing more of its remaining tasks. Starting with libgrypt 1.4.5, the SHA1 speed should have been improved [I'm testing with 1.4.5]. AES in 1.5.0 should support the AES-NI instructions from Intel, so on such processors it will be faster. Regards, Martin Kögler PS: Why does the trace/error infrastructure of libjpeg puts all parameters for formating the message into a structure and then calls via a pointer a functions (emit_message), which determines, if the message should be printed? ------------------------------------------------------------------------------ Free Software Download: Index, Search & Analyze Logs and other IT data in Real-Time with Splunk. Collect, index and harness all the fast moving IT data generated by your applications, servers and devices whether physical, virtual or in the cloud. Deliver compliance at lower cost and gain new business insights. http://p.sf.net/sfu/splunk-dev2dev _______________________________________________ Tigervnc-devel mailing list Tigervnc-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/tigervnc-devel
