On Tue, Dec 4, 2012 at 10:55 PM, Gustaf Neumann <neum...@wu.ac.at> wrote: > > The code in naviserver-connthreadqueue handles already read-aheads with SSL. > i have removed there these hacks already; i think, these were in part > responsible for the sometimes erratic response times with SSL.
Well, I think the thing here is one-upon-a-time SSL was considered computationally expensive (I don't know if it still is, with recent Intel cpus having dedicated AES instructions etc.). Read-ahead is good because you don't want an expensive conn thread waiting around for the whole request to arrive, packet by packet. But with SSL the single driver thread will be decrypting read-ahead data for multiple sockets and may run out of cpu, stalling the request pipeline, starving the conn threads. By making the SSL driver thread non-async you lose out on read-ahead as that all happens on the conn thread, but you gain cpu resources on a multi-cpu system (all of them, today). AOLserver 4.5 added a pool of read-ahead threads, one per-socket IIRC, to keep the benefits of read-ahead while gaining cpu parallelism. - does a single driver thread have enough computational resources to decrypt all sockets currently in read-ahead? This is going to depend on the algorithm. Might want to favour AES if you know your cpu has support. - which is worse, losing read-ahead, or losing cpu-parallelism? - if a read-ahead thread-pool is added, should it be one thread per-socket, which is simple, or one thread per-cpu and some kind of balancing mechanism? ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ naviserver-devel mailing list naviserver-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/naviserver-devel
