linux/arch/s390
Thomas Richter af90d7b69c s390/cpum_sf: remove flag PERF_CPUM_SF_FULL_BLOCKS
This flag is used to process only fully populated sampling buffers
when an sampling event is stopped on a CPU. By default the last sampling
buffer is also scanned for samples even if the sampling block full
indicator is not set in the trailer entry of a sampling buffer page.

This flag can be set via perf_event_attr::config1 field. It was never
used and never documented. It is useless now.

With PERF_CPUM_SF_FULL_BLOCKS:
When a process is scheduled off the CPU, the sampling is stopped and
the samples are copied to the perf ring buffer and marked invalid.
When stopped at the last full sample buffer page (which is
achieved with the PERF_CPUM_SF_FULL_BLOCKS options), the hardware
sampling will resume at the first free sample entry in the current,
partially filled sample buffer.

Without PERF_CPUM_SF_FULL_BLOCKS (default behavior):
The partially filled last sample buffer is scanned and valid samples
are saved to the perf ring buffer. The valid samples are marked invalid.
The sampling is resumed when the process is scheduled on this CPU.
Again the hardware sampling will resume at the first free sample entry in
the current, partially filled sample buffer.

Now the next interrupt handler invocation scans the
full sample block and saves the valid samples to the ring buffer.
It omits the invalid samples at the top of the buffer.
The default behavior is fully sufficient, therefore remove this feature.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2023-03-27 17:19:52 +02:00
..
appldata s390: simplify dynamic sysctl registration for appldata_register_ops 2023-03-20 10:56:49 +01:00
boot s390/kasan: move shadow mapping to decompressor 2023-03-20 11:02:51 +01:00
configs vfio-mdev: turn VFIO_MDEV into a selectable symbol 2023-01-23 11:26:29 -07:00
crypto This update includes the following changes: 2023-02-21 18:10:50 -08:00
hypfs s390/hypfs: remove unused info_blk_hdr__pcpus() function 2022-11-23 16:24:07 +01:00
include s390/cpum_sf: remove flag PERF_CPUM_SF_FULL_BLOCKS 2023-03-27 17:19:52 +02:00
kernel s390/cpum_sf: remove flag PERF_CPUM_SF_FULL_BLOCKS 2023-03-27 17:19:52 +02:00
kvm * Two more V!=R patches 2023-02-15 12:35:26 -05:00
lib s390/kprobes: replace kretprobe with rethook 2023-01-22 18:42:35 +01:00
mm s390/mm: make use of atomic_fetch_xor() 2023-03-20 11:12:49 +01:00
net s390/bpf: Implement bpf_jit_supports_kfunc_call() 2023-01-29 19:16:29 -08:00
pci s390/pci: clean up left over special treatment for function zero 2023-03-13 09:16:43 +01:00
purgatory s390/purgatory: Remove unused '-MD' and unnecessary '-c' flags 2023-01-26 12:43:05 +09:00
tools KVM: s390: Add facility 197 to the allow list 2022-07-13 15:25:25 +02:00
Kbuild
Kconfig s390: make use of CONFIG_FUNCTION_ALIGNMENT 2023-03-20 11:12:46 +01:00
Kconfig.debug
Makefile s390: always build relocatable kernel 2022-11-08 19:32:32 +01:00