On 04/15/2015 04:16 AM, Peter Zijlstra wrote:
> On Mon, Apr 13, 2015 at 09:38:01PM -0500, Suresh E. Warrier wrote:
>
>> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
>> index c9b3005..0a2d862 100644
>> --- a/kernel/trace/ring_buffer.c
>> ++
On 04/14/2015 12:13 PM, Peter Zijlstra wrote:
> On Mon, Apr 13, 2015 at 09:38:01PM -0500, Suresh E. Warrier wrote:
>> +static u64 *get_write_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
>> +unsigned long *flags)
>> +{
>> +if
When tracing the behavior of multiple fio jobs running in parallel
our performance team observed that some scsi_dispatch_cmd_done events
appeared to occur earlier, often several microseconds earlier, than
their associated scsi_dispatch_cmd_start event in the trace records.
Other interrupt events we
Introduce a new tunable nested_precise_ts that allows precise time
stamps to be recorded for nested trace writes.
The tunable is: /sys/kernel/debug/tracing/nested_precise_ts. By default,
it is zero and the behavior is disabled. Set the tunable to 1 in order
to get accurate timestamps.
Signed-off
This patch set provides supports a way to record precise timestamps
for nested writes and a tunable to enable the behavior.
Nested writes occur when a trace writer is preempted, usually through
an interrupt and the interrupt handler also writes its own trace. It has
been noticed on large systems w
On 03/24/2015 06:19 PM, Steven Rostedt wrote:
> On Tue, 24 Mar 2015 18:10:05 -0500
>
..
..
> There is no architecture where disabling interrupts is cheap. Actually,
> enabling them is the killer. Doing function tracing shows the impact of
> this rather well, as it would disable and enable interru
When tracing the behavior of multiple fio jobs running in parallel
our performance team observed that some scsi_dispatch_cmd_done events
appeared to occur earlier, often several microseconds earlier, than
their associated scsi_dispatch_cmd_start event in the trace records.
Other interrupt events we
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