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s390/cpum_sf: Add flag to process full SDBs only

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Add the PERF_CPUM_SF_FULL_BLOCKS flag to process only sample-data-blocks that
have the block-full-indicator bit set.  Sample-data-blocks that are partially
filled are discarded.  Use this flag if the sampling buffer is likely to be
shared among perf events that use different sampling modes.  In such
environments, flushing sample-data-blocks that are not completely filled, might
cause invalid-data-formats.

Setting PERF_CPUM_SF_FULL_BLOCKS prevents potentially invalid sampling data to
be processed but, in contrast, also discards valid samples in partially filled
sample-data-blocks.  Note that sample-data-blocks might not become full for
small sampling frequencies or for workload that is scheduled for tiny intervals.

To sample with the PERF_CPUM_SF_FULL_BLOCKS flag, set the perf->attr.config1
to 0x0004.  For example:

	perf record -e cpum_sf/config=0xB000,config1=0x0004/

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Hendrik Brueckner
2013-12-13 12:45:01 +01:00
committed by Martin Schwidefsky
parent 7e75fc3ff4
commit d7528862cf
2 changed files with 13 additions and 2 deletions
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2
arch/s390/include/asm/perf_event.h
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@@ -59,6 +59,7 @@ struct perf_sf_sde_regs {
#define PERF_CPUM_SF_DIAG_MODE 0x0002 /* Diagnostic-sampling flag */
#define PERF_CPUM_SF_MODE_MASK (PERF_CPUM_SF_BASIC_MODE| \
PERF_CPUM_SF_DIAG_MODE)
#define PERF_CPUM_SF_FULL_BLOCKS 0x0004 /* Process full SDBs only */
#define REG_NONE 0
#define REG_OVERFLOW 1
@@ -69,6 +70,7 @@ struct perf_sf_sde_regs {
#define SAMPL_RATE(hwc) ((hwc)->event_base)
#define SAMPL_FLAGS(hwc) ((hwc)->config_base)
#define SAMPL_DIAG_MODE(hwc) (SAMPL_FLAGS(hwc) & PERF_CPUM_SF_DIAG_MODE)
#define SDB_FULL_BLOCKS(hwc) (SAMPL_FLAGS(hwc) & PERF_CPUM_SF_FULL_BLOCKS)
/* Structure for sampling data entries to be passed as perf raw sample data
* to user space. Note that raw sample data must be aligned and, thus, might