Re: HyperThreading

[Venkatesh Srinivas <me@xxxxxxxxxxxxxxxxxxx>]

Sysbench OLTP is a very solid test; I'd love to see any results you get from it, either with Postgres or MySQL as a database server.

http://m-net.arbornet.org/~sv5679/sysbench_nmalloc_df.gif are results from the spring of last year, very early in the 2.7 branch, for Sysbench/OLTP with MySQL against Dfly. Despite the title of the graph, this was on an 8-core Xeon (Nehalem-based) system; also not shown on the graph are the UP kernel results -- the UP kernel with the old libc malloc had a more or less flat line at 650 transactions/sec (which was distressingly always faster than the SMP kernel!) and the UP kernel with the new libc malloc had a flat line at around 800 transactions/sec. With Google's tcmalloc, we had much better results, but I don't have those numbers handy.

We've really broken up the MP lock since then; the LWKT scheduler has been changed a lot (round-robin -> fair share); tokens have been reworked twice; and even the 4BSD scheduler has had work. I'd love to see if we're merely rearranging deck chairs or if we've actually improved matters...

-- vs