With kernel 2.6.24-rc6, volanoMark has much regression. 1) On 8-core stoakley: 17%; 2) On 16-core tigerton: 24%.
I bisected it down to patch fbdcf18df73758b2e187ab94678b30cd5f6ff9f9. It is to fix the bad cpu number in /proc/cpuinfo. As a matter of fact, this issue is already fixed by other 2 patches: 699d934d5f958d7944d195c03c334f28cc0b3669 and c0c52d28e05e8bdaa2126570c02ecb1a7358cecc. At the first glance, the patch looks good, at least no conflict with the other 2 patches. After double-checking it, I found in below call chain: smp_store_cpu_info => identify_cpu => init_intel => init_intel_cacheinfo. When CONFIG_X86_HT=y, init_intel_cacheinfo will uses cpuinfo_x86->cpu_index, which is initiated by smp_store_cpu_info. If with patch fbdcf18df73758b2e187ab94678b30cd5f6ff9f9, cpuinfo_x86->cpu_index is initiated after identify_cpu is called, so init_intel_cacheinfo just always initiates per_cpu(cpu_llc_id, 0) = l2_id or l3_id. Then, set_cpu_sibling_map will set bad llc_shared_map, so the core domain won't be built. By checking domain info from dmesg, it really confirms my consequence. >From this case, I really found that core domain could improve performance, at >least when testing by volanoMark. :) The solution is just to revert patch fbdcf18df73758b2e187ab94678b30cd5f6ff9f9, because other 2 patches which fixed the same issue are already in 2.6.24-rc5. -yanmin -- 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/
