From 4f206a0fabc3e806349add0996b3a999739559d2 Mon Sep 17 00:00:00 2001 From: Artem Bityutskiy Date: Wed, 25 Jul 2018 11:52:06 +0300 Subject: tools/power turbostat: fix bogus summary values This patch fixes a regression introduced in commit 8cb48b32a5de ("tools/power turbostat: track thread ID in cpu_topology") Turbostat uses incorrect cores number ('topo.num_cores') - its value is count of logical CPUs, instead of count of physical cores. So it is twice as large as it should be on a typical Intel system. For example, on a 6 core Xeon system 'topo.num_cores' is 12, and on a 52 core Xeon system 'topo.num_cores' is 104. And interestingly, on a 68-core Knights Landing Intel system 'topo.num_cores' is 272, because this system has 4 logical CPUs per core. As a result, some of the turbostat calculations are incorrect. For example, on idle 52-core Xeon system when all cores are ~99% in Core C6 (CPU%c6), the summary (very first) line shows ~48% Core C6, while it should be ~99%. This patch fixes the problem by fixing 'topo.num_cores' calculation. Was: 1. Init 'thread_id' for all CPUs to -1 2. Run 'get_thread_siblings()' which sets it to 0 or 1 3. Increment 'topo.num_cores' when thread_id != -1 (bug!) Now: 1. Init 'thread_id' for all CPUs to -1 2. Run 'get_thread_siblings()' which sets it to 0 or 1 3. Increment 'topo.num_cores' when thread_id is not 0 I did not have a chance to test this on an AMD machine, and only tested on a couple of Intel Xeons (6 and 52 cores). Reported-by: Vladislav Govtva Signed-off-by: Artem Bityutskiy Signed-off-by: Len Brown --- tools/power/x86/turbostat/turbostat.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/power') diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c index 81a1df0fb5e2..1b53a2489ebb 100644 --- a/tools/power/x86/turbostat/turbostat.c +++ b/tools/power/x86/turbostat/turbostat.c @@ -4838,7 +4838,7 @@ void topology_probe() siblings = get_thread_siblings(&cpus[i]); if (siblings > max_siblings) max_siblings = siblings; - if (cpus[i].thread_id != -1) + if (cpus[i].thread_id == 0) topo.num_cores++; if (debug > 1) -- cgit v1.2.3