Please CC me as I'm not subscribed. I have (what is to me) a strange and very repeatable slowdown for a CPU intensive benchmark on my system on newer kernels.
Hardware : Dell Precision 470. CPU 2x2.0GHz Quad Core Xeon E5335 CPUs Memory 4GB ECC RAM. OS Ubuntu x86_64 7.10 (Gutsy Gibbon) Compiler : gcc version 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2) Benchmark : A ray-trace is performed on 500 times on 17 separate scenes. Workload is distributed by tiling the framebuffer into N 32x32 pixel tiles. Each CPU grabs one of N tiles out of the queue and repeats until no jobs are left. Rendering is to a shared framebuffer (obviously this causes problems with caching). Locking and synchronization is done using pthreads. Other details: The system is cleanly booted for each run. No I/O is performed during the timed portions of the test. The benchmark does however read a model file from the drive and build a data structure from it before each timed portion. On the 2.6.22 series of kernels results are pretty much the same. On 2.6.23 series kernels I see a loss in speed of ~2% across the board. On 2.6.24-rc7 that loss in speed is perhaps very slightly worse (~3%). 2.6.22 Kernels tested: 22.9(Ubuntu Stock Kernel), 22.14, 22.15 2.6.23 Kernels tested: 23.1, 23.3, 23.13 2.6.24 Kernels tested: 24-rc7 I have my kernel compiled to use the SLAB allocator. All other tweaking options are set as defaults. My config files are available at http://vangogh.cs.tcd.ie/fowler/configs . Perhaps I'm configuring something wrong for the type of work I do? regards, Colin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
