On Fri, Aug 15, 2025 at 11:34:56AM -0500, Segher Boessenkool wrote:
> On Thu, Aug 07, 2025 at 03:16:35PM +0530, Madhavan Srinivasan wrote:
> > making them eligible for compiler optimization.
>
> You can instead use GCC for this. __builtin_ffs () exists since 2003,
Erm, 1992 actually, but stuff h
Hi!
On Thu, Aug 07, 2025 at 03:16:35PM +0530, Madhavan Srinivasan wrote:
> making them eligible for compiler optimization.
You can instead use GCC for this. __builtin_ffs () exists since 2003,
and has this attribute built-in, as well as tens of other optimisations
that the kernel thing misses.
On Mon, 11 Aug 2025 22:44:30 PDT (-0700), thomas.weisssc...@linutronix.de wrote:
All vDSO objects need the same treatment.
To make changes to both the list of objects and the list of removed flags
easier, introduce a helper variable.
Signed-off-by: Thomas Weißschuh
Reviewed-by: Alexandre Ghiti
On Mon, 11 Aug 2025 22:44:31 PDT (-0700), thomas.weisssc...@linutronix.de wrote:
All the other architectures supporting LTO (x86, arm64, loongarch) do not
use it for the vDSO.
Its is problematic for some upcoming compile-time validation of the
generated object code.
The LTO object files do not c
On Mon, 11 Aug 2025 22:44:19 PDT (-0700), thomas.weisssc...@linutronix.de wrote:
These constants are useful for cross-platform userspace, for example to
process ELF files during kernel cross-compilation.
Move them from the kernel-private architecture-specific header to the UAPI.
Signed-off-by:
On Wed, 13 Aug 2025 18:14:46 +0200, Wolfram Sang wrote:
> While working on a driver using regmap with MMIO, I wondered if I need
> to set 'fast_io' in the config. Turned out I don't need to, so I added
> documentation for it with commit ffc72771ff6e ("regmap: Annotate that
> MMIO implies fast IO"
On Mon, Aug 04, 2025 at 09:43:56AM -0700, Kees Cook wrote:
> Hi,
>
> While tracking down a problem where constant expressions used by
> BUILD_BUG_ON() suddenly stopped working[1], we found that an added static
> initializer was convincing the compiler that it couldn't track the state
> of the prio
> On 15 Aug 2025, at 5:47 PM, Venkat Rao Bagalkote
> wrote:
>
>
> On 15/08/25 2:03 pm, Athira Rajeev wrote:
>> The pseries Shared Processor Logical Partition(SPLPAR) machines can
>> retrieve a log of dispatch and preempt events from the hypervisor
>> using data from Disptach Trace Log(DTL) b
On 15/08/25 2:03 pm, Athira Rajeev wrote:
The pseries Shared Processor Logical Partition(SPLPAR) machines can
retrieve a log of dispatch and preempt events from the hypervisor
using data from Disptach Trace Log(DTL) buffer. With this information,
user can retrieve when and why each dispatch & p
Hi Christophe,
On Thu, Aug 14, 2025 at 03:43:09PM +0200, Christophe Leroy wrote:
> Le 12/08/2025 à 07:44, Thomas Weißschuh a écrit :
> > The compiler can emit absolute relocations in vDSO code,
> > which are invalid in vDSO code.
> > Detect them at compile-time.
>
> I'm a bit puzzled with this se
Hello Mani,
Sorry for the delayed reply.
I just came back from vacation.
On Thu, Jul 24, 2025 at 11:00:05AM +0530, Manivannan Sadhasivam wrote:
> On Fri, Jul 18, 2025 at 12:39:50PM GMT, Niklas Cassel wrote:
> > On Fri, Jul 18, 2025 at 12:28:44PM +0200, Niklas Cassel wrote:
> > > On Tue, Jul 15, 2
Documentation for vpa-dtl (Virtual Processor Area - Dispatch Trace Log)
PMU interface. And how it can be used to collect the distrace trace log
entries in perf data, how to process/report as part of perf report/perf
script.
Signed-off-by: Athira Rajeev
---
Documentation/arch/powerpc/index.rst
Enable perf script to present the DTL entries. Process the
dispatch trace log details in arch_perf_sample__fprintf_synth_evt()
defined in buiultin-script.c file for config value:
PERF_SYNTH_POWERPC_VPA_DTL.
Sample output:
./perf record -a -e sched:*,vpa_dtl/dtl_all/ -c 10 sleep 1
[
Introduce arch_perf_sample__fprintf_synth_evt to add support for
printing arch specific synth event details. The process_event()
function in "builtin-script.c" invokes perf_sample__fprintf_synth() for
displaying PERF_TYPE_SYNTH type events.
if (attr->type == PERF_TYPE_SYNTH && PRINT_FIELD(SYNTH
Create samples from DTL entries for displaying in perf report
and perf script. When the different PERF_RECORD_XX records are
processed from perf session, powerpc_vpadtl_process_event() will
be invoked. For each of the PERF_RECORD_XX record, compare the timestamp
of perf record with timestamp of top
When the Dispatch Trace Log data is collected along with other events
like sched tracepoint events, it needs to be correlated and present
interleaved along with these events. Perf events can be collected
parallely across the CPUs. Hence it needs to be ensured events/dtl
entries are processed in tim
Dispatch Trace Log details are captured as-is in PERF_RECORD_AUXTRACE
records. To present dtl entries as samples, create an event with name as
"vpa-dtl" and type PERF_TYPE_SYNTH. Add perf_synth_id,
"PERF_SYNTH_POWERPC_VPA_DTL" as config value for the event. Create a
sample id to be a fixed offset f
Add vpa dtl pmu auxtrace process function for "perf report -D".
The auxtrace event processing functions are defined in file
"util/powerpc-vpadtl.c". Data structures used includes "struct
powerpc_vpadtl_queue", "struct powerpc_vpadtl" to store the auxtrace
buffers in queue. Different PERF_RECORD_XXX
The powerpc PMU collecting Dispatch Trace Log (DTL) entries makes use of
AUX support in perf infrastructure. The PMU driver has the functionality
to collect trace entries in the aux buffer. On the tools side, this data
is made available as PERF_RECORD_AUXTRACE records. This record is
generated by "
Handle the case when the aux buffer is going to be full and
data needs to be written to the data file. perf_aux_output_begin()
function checks if there is enough space depending on the values of
aux_wakeup and aux_watermark which is part of "struct perf_buffer".
Inorder to maintain where to write t
vpa dtl pmu has one hrtimer added per vpa-dtl pmu thread. When the
hrtimer expires, in the timer handler, code is added to save the DTL
data to perf event record via vpa_dtl_capture_aux() function.
The DTL (Dispatch Trace Log) contains information
about dispatch/preempt, enqueue time etc. We direct
vpa dtl pmu has one hrtimer added per vpa-dtl pmu thread. When the
hrtimer expires, in the timer handler, code is added to save the DTL
data to perf event record. DTL (Dispatch Trace Log) contains information
about dispatch/preempt, enqueue time etc. We directly copy the DTL
buffer data as part of
From: Kajol Jain
Details are added for the vpa_dtl pmu event and format
attributes in the ABI documentation.
Signed-off-by: Kajol Jain
---
.../sysfs-bus-event_source-devices-vpa-dtl| 25 +++
1 file changed, 25 insertions(+)
create mode 100644
Documentation/ABI/testing/sys
From: Kajol Jain
The pseries Shared Processor Logical Partition(SPLPAR) machines
can retrieve a log of dispatch and preempt events from the
hypervisor using data from Disptach Trace Log(DTL) buffer.
With this information, user can retrieve when and why each dispatch &
preempt has occurred. Added
The pseries Shared Processor Logical Partition(SPLPAR) machines can
retrieve a log of dispatch and preempt events from the hypervisor
using data from Disptach Trace Log(DTL) buffer. With this information,
user can retrieve when and why each dispatch & preempt has occurred.
The vpa-dtl PMU exposes t
From: Aboorva Devarajan
- Define accessor function get_boot_tb() to safely return boot_tb.
- Tag boot_tb as __ro_after_init (only initialized once and never updated).
- Add a debug log to output the boot timebase during initialization.
Signed-off-by: Aboorva Devarajan
---
arch/powerpc/include/
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