út 10. 12. 2024 v 22:04 odesílatel Sasha Levin <sashal@xxxxxxxxxx> napsal: > > This is a note to let you know that I've just added the patch titled > > rtla/timerlat: Make timerlat_top_cpu->*_count unsigned long long > > to the 6.6-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > The filename of the patch is: > rtla-timerlat-make-timerlat_top_cpu-_count-unsigned-.patch > and it can be found in the queue-6.6 subdirectory. > Could you also add "rtla/timerlat: Make timerlat_hist_cpu->*_count unsigned long long", too (76b3102148135945b013797fac9b20), just like we already have in-queue for 6.12? It makes no sense to do one fix but not the other (clearly autosel AI won't take over the world yet). > If you, or anyone else, feels it should not be added to the stable tree, > please let <stable@xxxxxxxxxxxxxxx> know about it. > > > > commit 0b8030ad5be8c39c4ad0f27fa740b3140a31023b > Author: Tomas Glozar <tglozar@xxxxxxxxxx> > Date: Fri Oct 11 14:10:14 2024 +0200 > > rtla/timerlat: Make timerlat_top_cpu->*_count unsigned long long > > [ Upstream commit 4eba4723c5254ba8251ecb7094a5078d5c300646 ] > > Most fields of struct timerlat_top_cpu are unsigned long long, but the > fields {irq,thread,user}_count are int (32-bit signed). > > This leads to overflow when tracing on a large number of CPUs for a long > enough time: > $ rtla timerlat top -a20 -c 1-127 -d 12h > ... > 0 12:00:00 | IRQ Timer Latency (us) | Thread Timer Latency (us) > CPU COUNT | cur min avg max | cur min avg max > 1 #43200096 | 0 0 1 2 | 3 2 6 12 > ... > 127 #43200096 | 0 0 1 2 | 3 2 5 11 > ALL #119144 e4 | 0 5 4 | 2 28 16 > > The average latency should be 0-1 for IRQ and 5-6 for thread, but is > reported as 5 and 28, about 4 to 5 times more, due to the count > overflowing when summed over all CPUs: 43200096 * 127 = 5486412192, > however, 1191444898 (= 5486412192 mod MAX_INT) is reported instead, as > seen on the last line of the output, and the averages are thus ~4.6 > times higher than they should be (5486412192 / 1191444898 = ~4.6). > > Fix the issue by changing {irq,thread,user}_count fields to unsigned > long long, similarly to other fields in struct timerlat_top_cpu and to > the count variable in timerlat_top_print_sum. > > Link: https://lore.kernel.org/20241011121015.2868751-1-tglozar@xxxxxxxxxx > Reported-by: Attila Fazekas <afazekas@xxxxxxxxxx> > Signed-off-by: Tomas Glozar <tglozar@xxxxxxxxxx> > Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > > diff --git a/tools/tracing/rtla/src/timerlat_top.c b/tools/tracing/rtla/src/timerlat_top.c > index a84f43857de14..0915092057f85 100644 > --- a/tools/tracing/rtla/src/timerlat_top.c > +++ b/tools/tracing/rtla/src/timerlat_top.c > @@ -49,9 +49,9 @@ struct timerlat_top_params { > }; > > struct timerlat_top_cpu { > - int irq_count; > - int thread_count; > - int user_count; > + unsigned long long irq_count; > + unsigned long long thread_count; > + unsigned long long user_count; > > unsigned long long cur_irq; > unsigned long long min_irq; > @@ -237,7 +237,7 @@ static void timerlat_top_print(struct osnoise_tool *top, int cpu) > /* > * Unless trace is being lost, IRQ counter is always the max. > */ > - trace_seq_printf(s, "%3d #%-9d |", cpu, cpu_data->irq_count); > + trace_seq_printf(s, "%3d #%-9llu |", cpu, cpu_data->irq_count); > > if (!cpu_data->irq_count) { > trace_seq_printf(s, "%s %s %s %s |", no_value, no_value, no_value, no_value); > Thanks, Tomas
